Islamic Fiqh > Purification (Tahara) > Water: categories and rulings > Altered water and its uses
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Updated on 24 September 2026 at 1:14 PM
As for water heated by other than the sun, or heated by means of an impurity, the jurists differed over whether its use is permitted without dislike. The Malikis, the Shafi'is, the Hanbalis and Abu Hanifa hold that water heated by fire is not disliked for use, because no prohibition is established concerning it and because the fume departs through the strength of its effect; the Shafi'is and Abu Hanifa added: even if the heating were by an impurity, while the Malikis disliked that, namely the heating by impurity (al-Sharh al-Kabir, 1/74; Mawahib al-Jalil, 1/80; al-Hawi al-Kabir, 1/41; Nihayat al-Muhtaj, 1/71; Mughni al-Muhtaj, 1/81; Rawdat al-Talibin, 1/142; hashiya of al-Jamal, 1/36; Kifayat al-Akhyar, p. 54; al-Mughni, 1/41; Majmu al-Fatawa, 21/612).
The Hanbalis divided water heated by means of an impurity into three cases, as Ibn Qudamah set out. The first: some part of the impurity is verified to have reached the water: it defiles it if the water is small. The second: nothing is verified to have reached the water, but the barrier is not solid: the water remains on the original purity, and its use is disliked. The third: the barrier is solid: al-Qadi said it is disliked, while al-Sharif Abu Jafar and Ibn Aqil chose that it is not, because there is no uncertainty about its impurity, unlike the case before it. Abu al-Khattab mentioned two narrations on the dislike of water heated by impurity taken absolutely (al-Mughni, 1/42).
Shaykh al-Islam Ibn Taymiyyah said: water heated by means of an impurity is pure; but is it disliked or not? Two views, which are two narrations from Ahmad: the first, it is not disliked, and it is the view of Abu Hanifa and al-Shafi'i; the second, it is disliked, and it is the madhhab of Malik. The dislike has two grounds. The first: the fear that something of the impurity may have reached the water, in which case it is disliked because of the possibility of its defilement; on this basis, if there is a solid barrier between the hearth and the fire, there is no dislike: such is the way of al-Sharif Abu Jafar, Ibn Aqil and others. The second: the cause of the dislike is that using an impurity is itself disliked, and the heat came about through a disliked act: such is the way of al-Qadi Abu Yala; the cooking of food with impure fuel is like it, for the cooking of food is like the heating of water (Majmu al-Fatawa, 21/612 and 613).
Fourth category: mixed water, mixed either with something pure or with something impure. Water mixed with the pure is either avoidable or unavoidable, and each of the two either changes through the mixture of the pure or does not; water mixed with the impure either changes or does not, and the unchanged is either small or large.
First division: water mixed with something pure and unchanged. The jurists of the four schools agree that if something pure mixes with water and does not change it, because of its smallness, it does not prevent purification with it, for the water remains upon its unrestricted state.
Second division: water mixed with an unavoidable pure substance and changed. The jurists of the four schools agree that if a pure substance that cannot be guarded against mixes with it, like algae, moss and all that grows in the water, likewise tree leaves that fall into the water or that the wind casts into it, what the torrents draw and cast into it, of sticks and straw and the like, and what lies in the bed of the water, like sulphur and other things, over which the water flows and changes, or what lies in the land where the water stands: purification with it is permitted, for it is hard to guard against it (al-Hidaya, 1/18; al-Bahr al-Ra'iq, 1/71; al-Sharh al-Saghir, 1/23; al-Majmu, 2/56; al-Muhadhdhab, 1/5; al-Mughni, 1/37).
Third division: water mixed with an avoidable pure substance. The jurists differed over water changed by an avoidable pure substance, like saffron and soap and the like, in one of its attributes, its taste, colour or smell: is it pure and purifying, so that purification with it is valid, or pure in itself without being purifying for other things, lifting no hadath and removing no impurity? Two views.
The first view: the Hanafis and Ahmad in one narration held it pure and purifying; Shaykh al-Islam Ibn Taymiyyah said: this view is the correct one (Majmu al-Fatawa, 21/25). They argued from the word of Allah:
“If you do not find water, then perform tayammum”
Surah An-Nisa, 43
This is general over every water, because “water” is an indefinite in a context of negation, and the indefinite in negation is general: tayammum is therefore not permitted in its presence (al-Mughni, 1/36). They also argued from the saying of the Prophet concerning the man whom his she-camel threw down and who died:
Wash him with water and sidr (lote-tree leaves).Reported by al-Bukhari (1206) and Muslim (1206)
Were it not purifying he would not have ordered washing with it, for the washing of the dead is only valid with what wudu is valid with; and it is purifying water that a pure substance has mixed without removing from it the name of water, its fluidity or its flow: it resembles water changed by oil (Tabyin al-Haqa'iq, 1/21; al-Bahr al-Ra'iq, 1/71; hashiyat al-Tahtawi, 1/18; Sharh Fayd al-Qadir, 1/72; al-Mughni, 1/36). To this is added what Umm Hani related:
The Messenger of Allah, and Maymunah with him, bathed from a single vessel, a bowl bearing traces of dough.Authentic hadith: reported by Ibn Majah (1/37), al-Nasa'i in al-Kubra (242), al-Bayhaqi in al-Sunan al-Kubra (1/17) and Ibn Hibban in his Sahih (1245)
The second view: the Malikis, the Shafi'is and the Hanbali madhhab held it pure but not purifying, like meat water and bean water: its use is permitted in ordinary matters, like cooking and the like, but not for wudu or ghusl. The author of As'hal al-Madarik, Abu Bakr ibn al-Hasan ibn Abdullah al-Kishnawi the Maliki, said: water changed by something pure, like milk, is pure in itself, not purifying: it is used in ordinary matters, like cooking and drinking, and is not used in acts of worship, like wudu and ghusl (As'hal al-Madarik, 1/38; Mawahib al-Jalil, 1/59).
Al-Nawawi said: what we have mentioned, the prevention of purification with water changed by the mixture of what is not purifying while the water has no need of it, is our madhhab, the madhhab of Malik, of Dawud, and of Ahmad in the more correct of the two narrations. Abu Hanifa said: purification with water changed by saffron is permitted, and with every pure substance, whether the change be little or great, on condition that it flow, and not if thick, except meat broth and bean broth (al-Majmu, 2/59 and 60).
Their proof, namely that of the Malikis, the Shafi'is and the Hanbalis in the madhhab: it is water changed by the mixture of what is not purifying yet avoidable, so wudu with it is not valid, like boiled meat water and bean water; and the mixing of water with an avoidable pure substance, like saffron and the like, removes its unrestrictedness: hence the one who swears not to drink water does not break his oath by drinking it (al-Mughni, 1/36; al-Insaf, 1/32).
Fourth division: water changed by the proximity of a pure substance. If water changes through the proximity of something pure, like oils and the solid pure substances like aloe wood and camphor, when they neither perish in the water nor melt into it, it is pure and purifying according to the Hanafis, the Hanbalis and some Malikis, and it is the more apparent view among the Shafi'is: this change comes only from the side of proximity, so it does no harm, for it does not prevent the unrestricted name of water from applying to it: it resembles water scented by something fragrant at its side (Tabyin al-Haqa'iq, 1/20; al-Sharh al-Saghir, 1/22; hashiya of al-Dusuqi, 1/59; al-Hawi al-Kabir, 1/52 and 53; al-Muhadhdhab, 1/5; al-Majmu, 2/61; Sharh al-Minhaj, 1/19; al-Mughni ma'a al-Sharh, 1/38). The Malikis in their relied-upon view, and the Shafi'is in the view opposing the more apparent, held it pure but not purifying, by analogy with water mixed with saffron (same references).
Continuing the previous case: if the adjacent pure substance perishes and melts into the water, it has the ruling of the pure that is not purifying: its use is not permitted for lifting hadath. Ibn Qudamah said: what changes the water by its proximity without mixture, the oils in all their varieties and the solid pure substances like aloe wood, camphor and ambergris, when they neither perish in the water nor melt into it, does not remove it from its unrestricted state, because it is a change of proximity, like something fragrant scenting at its side, and we know of no disagreement in this. In the same category as water changed by oil come water changed by tar, pitch and wax, for they contain an oiliness that changes the water by way of proximity without preventing, like oil (al-Mughni, 1/38).
First division: water mixed with impurity, one of whose attributes has changed. The people of knowledge agree that if an impurity mixes with water and changes one of its attributes, the water is impure, whether it is small or large. Ibn al-Mundhir said: they agreed that water, small or large, into which an impurity falls and changes its taste, colour or smell, is defiled as long as it remains so (al-Ijma, 21; Majmu al-Fatawa, 21/30).
Second division: water mixed with impurity, none of whose attributes, colour, taste or smell, has changed: is purification with it permitted or not? Two views.
The first view: it is pure, whether large or small; it is a narration from Imam Malik and one of the two narrations from Imam Ahmad, chosen by a group of his companions, defended by Ibn Aqil and chosen by Shaykh al-Islam Ibn Taymiyyah; with them, some Shafi'is like Ibn al-Mundhir, al-Ghazali and al-Ruyani (Bidayat al-Mujtahid, 1/46; Majmu al-Fatawa, 21/30 and 33; al-Majmu, 2/73; al-Mughni, 1/50; Kifayat al-Akhyar, p. 56; al-Ifsah, 1/37). Their proof is what Abu Sa'id al-Khudri related: it was said to the Prophet: should we perform wudu from the well of Buda'a, a well into which menstrual cloths, the flesh of dogs and filth are thrown? And the hadith already cited, whose wording is general over the small and the large and over all impurities (Majmu al-Fatawa, 21/33).
Al-Dusuqi set out: the small amount of water, which is below the measure of the vessel of wudu or ghusl, into which a small impurity, like a drop, has fallen without changing it: its use is disliked for lifting a hadath or for a ruling of impurity, and for anything dependent on purifying water, like the recommended purifications. As for its use in ordinary matters, there is no dislike in it: the dislike is specific to what depends on purifying water. He then summed up: the dislike is bound by seven conditions:
If one of these conditions is absent, there is no dislike (hashiya of al-Dusuqi, 1/70 and 71).
The second view: a distinction between the water being small and its being large: if the water is small it is defiled, and if large it is not. This is the view of the Hanafis, and it is the second narration from Malik, the madhhab among the Shafi'is, and the well-known position among the Hanbalis (Mukhtasar al-Quduri, 13; Bada'i al-Sana'i, 1/250 and 253; hashiya of Ibn Abidin, 1/340; al-Majmu, 2/70 and 72; Mughni al-Muhtaj, 1/84 and 85; Bidayat al-Mujtahid, 1/46; Kifayat al-Akhyar, p. 56; al-Mughni, 1/47; Majmu al-Fatawa, 21/30; al-Ifsah, 1/37). The holders of this view differed over the dividing line between the small and the large, in three views.
The first view, that of the Hanafis: water such that some of it reaches some of it, that is, whose parts mingle with one another, is small, and what does not is large. Any water some of which does not reach some of it, that is, one side of which does not move when the other side moves, is large: it is not defiled by the falling of impurity into it; and water whose parts reach one another is small: it is defiled by impurity falling into it. Its measure in surface is ten cubits by ten cubits; below that it is defiled even if no trace of the impurity appears in it, and likewise if it is flowing and the trace appears in it; the trace: taste, colour or smell, for these do not remain with the current; and its depth must be such that its bed is not exposed by scooping from it (Bada'i al-Sana'i, 1/252 and 253; Mukhtasar al-Quduri, 13).
The Hanafis differed over the explanation of this mingling. Al-Kasani said: they differed over the explanation of the mingling, then the narrations from our companions agreed that the mingling is assessed by movement: if the water is such that, were one side of it moved, the other side would move, then it is of the kind whose parts reach one another; and they differed only over the manner of the movement: Abu Yusuf related from Abu Hanifa that the movement is assessed by bathing, without violence, and Muhammad related from him that it is assessed by wudu, and in one narration, by the hand, without bathing or wudu. As for the great basin, one side of which does not move when the other moves: if an impurity falls upon one of its two sides, wudu is permitted from the other side, because the apparent case is that the impurity does not reach it (Bada'i al-Sana'i, 1/252 and 253; Mukhtasar al-Quduri, 13).
Their proofs: the hadith of Abu Hurayrah, that the Prophet said:
When one of you wakes from sleep, let him not dip his hand into the vessel until he has washed it three times, for he does not know where his hand spent the night.Reported by Muslim (87)
They said: were the water of the vessel not defiled by the dipping, the prohibition, motivated by the suspicion of impurity, would be meaningless; and it is known that the water of a vessel, when a human being moves it from one of its two sides, carries the movement through to the other side. Added to this are the widely related reports commanding the washing of the vessel from the licking of the dog, even though its colour, taste and smell do not change (Bada'i al-Sana'i, 1/251; Tuhfat al-Fuqaha, 1/56; Mukhtasar al-Quduri, 13).
The second view, that of Imam Malik: if its colour, taste or smell has changed, it is small, and if it is unchanged, it is large (Bidayat al-Mujtahid, 1/46; al-Sharh al-Kabir, 1/71). The third view, that of the Shafi'is and the Hanbalis: water that reaches two qullahs is large, and below that it is small. Their proof is what Ibn Umar related: the Prophet was asked about the water found in the desert plain and frequented by the beasts and the cattle:
When water is two qullahs, it carries no impurity; and in a narration: nothing defiles it.Authentic hadith: reported by al-Nasa'i, Abu Dawud (63 and 64), al-Tirmidhi (67), Ibn Majah (517), Ahmad (2/27), al-Darimi (731), al-Hakim in al-Mustadrak (1/224), who graded it authentic under the conditions of the two shaykhs with al-Dhahabi concurring, al-Bayhaqi in al-Kubra (1/261) and al-Daraqutni (1/19 and 20); authenticated by Ibn Hibban (1245) and by al-Albani in Sahih Sunan Abi Dawud (56); graded hasan by al-Nawawi in al-Majmu (2/70); al-Khattabi said: it suffices as witness to its authenticity that the leading stars of the hadith scholars authenticated it, held by it and relied upon it in delimiting water, they who are the authority and the reliance in this chapter (al-Majmu, 2/76)
Ibn Qudamah said: its delimitation at two qullahs indicates that below them it is defiled, for if two qullahs and what is below them had the same ruling, the delimitation would serve no purpose (al-Mughni, 1/52). Al-Shirazi said: two qullahs of water can be guarded from impurity in containers, while a large amount cannot be guarded from impurity: hence two qullahs is made the dividing line between them (al-Majmu, 2/70).
A remark of Ibn Hajar: his words “it carries no impurity” mean: it is not defiled by the falling of impurity into it, as explained in the other narration, which Abu Dawud, Ibn Hibban and others related: “when water reaches two qullahs, it does not become impure”; the sense is: it does not accept impurity, rather it repels it from itself; and were the meaning that it is too weak to bear it, the restriction to two qullahs would be meaningless, what is below them being more deserving of that; and it was said: it does not accept the ruling of impurity, as in the word of Allah:
“The example of those who were entrusted with the Torah and then did not carry it is like the example of the donkey carrying books”
Surah Al-Jumu'ah, 5
that is: they did not accept its ruling (Talkhis al-Habir, 1/140).
The jurists further differed over water mixed with impurity according to its two states of flowing and stagnation. First, the madhhab of the Hanafis: they distinguish between the water being flowing or stagnant. If an impurity falls into water that is flowing, and the impurity is not visible, and none of the attributes of the water has changed, it is pure according to them. Imam al-Kasani al-Hanafi said: if the impurity falls into the water and the water is flowing and the impurity is not visible, like urine and wine and the like, it is not defiled so long as its colour, taste or smell has not changed, and wudu is made from it from whichever place, from the side on which the impurity fell or from another side.
Muhammad mentioned it in the Book of Drinks: if a man were to pour a large clay jar of wine into the Euphrates, and another man below him performs wudu: if its colour, taste or smell has changed, it is not permitted, and when unchanged, it is permitted. And from Abu Hanifa concerning the uneducated man who urinated into flowing water while a man below him performs wudu with it: “there is no harm in it”, and this is because flowing water is of the kind whose parts do not reach one another: the water he performs wudu with may be impure and may be pure, and water is pure in origin. If the impurity is visible, like a carcass and the like: if all of the water flows over the carcass, wudu below the carcass is not permitted, for it is impure with certainty, and the impure is not purified by the flowing; and if most of it flows over the carcass, the same applies, for what counts is the predominant; and if the lesser part flows over the carcass while the greater flows over the pure, wudu below the carcass is permitted, for what is overcome is treated as nonexistence in the rulings of the Sharia; and if half of it, or less than half, flows over it, then by analogy wudu with it is permitted, for the water was pure with certainty and is not judged impure by doubt, while according to istihsan it is not permitted, as a precaution. The shaykhs differed over the definition of flowing: some of them said: it is that it flows along with the straw and the leaves (Bada'i al-Sana'i, 1/252 and 253; Mukhtasar al-Quduri, 13). The large clay jar, the khabiyah, is a big earthen vessel into which water, oil and the like are poured (Mujam Lughat al-Fuqaha, 191).
On the Maliki side, it follows from the conditions of al-Dusuqi that if the water is flowing and an impurity has settled in it without changing it, its use is not disliked (hashiya of al-Dusuqi, 1/70 and 71).
Third, the madhhab of the Shafi'is: al-Shirazi said in al-Muhadhdhab: when an impurity falls into the water, the water is either stagnant, or flowing, or part of it stagnant and part flowing. If it is stagnant, the impurity is examined. If it is an impurity the senses perceive, like wine and urine, or a carrion with flowing blood, one looks: if one of the attributes of the water changes, of taste, colour or smell, it is impure, according to the saying of the Prophet: “Water is tahur; nothing defiles it except what changes its taste or its smell”, the hadith cited above: the text mentions taste and smell, and colour is measured upon them, being of their meaning. If part of the water changes without another part, all of it is defiled, for it is one water: it cannot be that part of it is defiled and part not. If nothing changes: if the water is below two qullahs it is impure, and if it is two qullahs or more it is pure, according to “when water is two qullahs it carries no impurity”, and because two qullahs of water can be guarded from impurity in containers, while the large amount cannot: hence two qullahs is made the dividing line between them.
Then he said: if the impurity is of the kind the senses do not perceive, there are three positions among our companions: some of them said: it has no ruling, because it cannot be guarded against: it is like the dust of dung; and some of them said: its ruling is the ruling of the rest of the impurities, because it is a certain impurity: it is like the impurity the senses perceive; and some of them said: two views apply in it.
He then set out its ruling when the water is flowing, and said: if the water is flowing and in it is a flowing impurity, like a carcass carried by the current and changed, the water before it is pure, for it has not reached the impurity: it is like the water poured over impurity from a jug; and the water after it is also pure, for the impurity has not reached it. As for the water surrounding the impurity, above it, below it, to its right and to its left: if it is two qullahs and unchanged, it is pure, and if below that, it is impure like the stagnant. Al-Nawawi explained (al-Majmu, 2/121) that the term for the flowing mass, with kasra of the jim, is the surge of water between the two banks of the river in width, as our companions explained it. Abu al-Abbas ibn al-Qass said: there is another view, which he stated in the earlier doctrine: flowing water is not defiled except by change, for it is water that came upon the impurity and is not defiled without change, like the water with which impurity is removed.
Among the Hanbalis: it is said in al-Insaf: this disagreement concerns stagnant water; as for the flowing, it is related from Ahmad that it is like the stagnant: if the whole of it reaches two qullahs, it removes the impurity even if unchanged, and otherwise not: and this is the madhhab. It is said in al-Hawi al-Saghir: a small flowing amount is not defiled before its change, according to the more correct of the two narrations; and from Ahmad: it is assessed as a surge in its own right, chosen by al-Qadi and his companions, and he said: it is the madhhab. Al-Zarkashi said: it is the choice of the majority (al-Insaf, 1/56 and 57; al-Kafi, 1/9; al-Mubdi, 1/53; al-Mughni, 1/58).
If vessels are mixed together in proximity, some of them containing purifying water and some of them impure water, the matter becomes confused for the person, and he has no ability to find other purifying water than what is in some of them: the jurists expressed five views, of which four are developed in this leaf.
The first view: he must examine and scrutinize to know which of them is the purifying one; if, after examination, the purifying character of one of them prevails in his opinion through an apparent sign, it is permitted for him to purify himself with it, and not otherwise. This is the madhhab of the majority of the Shafi'is, and it is the view of Ibn al-Mawwaz, Sahnun and Ibn al-Arabi among the Malikis. Al-Nawawi said: when two waters, pure and impure, are confused, the correct, textual position, on which the majority decisively settled and upon which the texts of al-Shafi'i converge: purification is not permitted with either of them except if, after examination, its purity prevails in his opinion through an apparent sign; if his assumption rests on something other than an apparent sign, purification with it is not permitted; and it is the same in our view whether the number of pure ones is greater or lesser, to the point that were one pure vessel confused with a hundred impure vessels, he would scrutinize among them; and likewise foods and garments: this is our madhhab, and to this effect spoke some of the companions of Malik (al-Majmu, 2/164 and 165; al-Umm, 1/11; Mughni al-Muhtaj, 1/59; Mawahib al-Jalil, 1/171; Tahdhib al-Furuq, 1/228).
Their proof is the word of Allah:
“If you do not find water, then perform tayammum”
Surah An-Nisa, 43
Now this is one who has found water, so tayammum is not permitted, and examination is obligatory; and purification is a condition of the validity of prayer that can be attained through examination: it is therefore obligatory, by analogy with the qiblah, with ijtihad in the rulings and with the assessment of damages, even if error may occur (al-Majmu, 2/167).
The second view: examination and scrutiny are obligatory upon him when the vessels of purifying water are more numerous than the vessels of impure water; if the vessels of purifying water are equal in number to the vessels of impure, or fewer, scrutiny is not permitted him: he performs tayammum. So said the Hanafis, and it is the view of Abu Ali al-Najjad among the Hanbalis (hashiyat al-Tahtawi on Maraqi al-Falah, 1/23; al-Mughni, 1/84).
The third view: scrutiny is not permitted in confused waters, taken absolutely: all of it is left aside and tayammum is performed. It is one of the two views of Sahnun among the Malikis, the view of Abu Thawr and al-Muzani among the Shafi'is, and the view of Imam Ahmad and most of his companions (Mawahib al-Jalil, 1/171; al-Qawanin al-Fiqhiyya, 38; al-Majmu, 2/165; al-Mughni, 1/85). Their proof: were he to examine, he might fall upon the impure; and a pure confused with an impure forbids scrutiny, like water confused with urine (al-Majmu, 2/165). These then differed among themselves: Ahmad, in one of the two narrations: no tayammum until he pours out the water, to establish the absence of water; the second: he may perform tayammum before that, chosen by Abu Bakr; Ibn Qudamah said: it is the correct view, for he is not able to use the pure one; Sahnun, Abu Thawr and al-Muzani: he performs tayammum and prays with no repetition, even if he does not pour it out, for it is as nonexistent (al-Majmu, 2/165; al-Mughni, 1/86; Mawahib al-Jalil, 1/171).
The fourth view: he performs wudu by the number of the impure vessels plus one vessel, meaning that he performs wudu from one of them and prays, then performs wudu from another and prays, doing so by the number of the impure plus one. Thus, if the vessels are five and the impure among them two, he performs wudu from three of them and prays with each wudu one prayer; and if the impure are three, he performs wudu from four of them and prays with each. The fifth view announced by the encyclopedia is not developed in this leaf.
The jurists differed over the ruling of a man performing wudu with the remainder of a woman's purifying water: is it permitted or not? The majority of jurists, Hanafis, Malikis, Shafi'is and Hanbalis in one narration, hold that it is permitted for a man to perform wudu with the remainder of a woman's wudu, even if she was alone with the water, because Muslim related in his Sahih:
The Messenger of Allah used to bathe with the remainder of Maymunah's water.Reported by Muslim (323)
And because of the words of Maymunah: I bathed from a basin and some water remained in it; the Prophet came to bathe, and I said: I have already bathed from it; he said: water carries no janabah (authentic hadith: reported by al-Tirmidhi (65), Ibn Majah (370), al-Darimi (734), Ahmad (6/330) and Ibn Hibban in his Sahih (4/73 and 74)); and because it is purifying water with which it is permissible for the woman to perform wudu, so it is permissible for the man, like the remainder of a man (al-Majmu, 2/220 and 221; al-Muhadhdhab, 1/31; al-Mabsut, 1/62; al-Mughni, 1/278; Mawahib al-Jalil, 1/52; al-Ifsah, 1/54; Sharh Sahih Muslim, 4/3; Ahkam al-Quran of Ibn al-Arabi, 3/442). Added to this is what is related from Ibn Umar, who used to say:
Men and women used to perform wudu, in the time of the Messenger of Allah, from a single vessel, all together.Reported by al-Bukhari (190) and Abu Dawud (79), whose wording it is
Ibn Abd al-Barr said: in this hadith is clear evidence for invalidating the statement of those who say that wudu is not performed with a woman's remainder, for when the two of them scooped together from a single vessel, each of the two performed wudu with the other's remainder (al-Istidhkar, 1/169).
The Hanbalis, in the madhhab, hold that it is not permissible for a man to perform wudu with the remainder of a woman's purifying water when she was alone with it; if they were both together, there is no harm (al-Mughni ma'a al-Sharh, 1/278; Sharh al-Zarkashi, 1/80; Manar al-Sabil, 1/15; al-Ifsah, 1/54; al-Awsat, 1/292). Their proof is what al-Hakam ibn Amr related:
The Prophet forbade that a man perform wudu with the remainder of a woman's purification.Authentic hadith: reported by Abu Dawud (82), al-Tirmidhi (64) and Ibn Majah (373)
Ibn Hajar said in al-Fath (1/360): the hadiths of prohibition are to be carried upon what drips from the limbs, and the permission upon what remains of the water; thus al-Khattabi reconciled; or the prohibition is carried upon discouragement, to reconcile the evidences, and Allah knows best.
As for a woman's wudu with the remainder of a man's purifying water, it is permissible by consensus. Al-Nawawi said: the purification of a woman with the remainder of a man's purification is permissible by consensus (Sharh Sahih Muslim, 4/3; see Fath al-Bari, 1/359).