Doubt in prayer and the prostration of forgetfulness

The rule of doubt

The Prophet set the rule: "when he doubts in his prayer and does not know how many rak'as he prayed, let him discard the doubt and build on certainty, then prostrate twice before saluting" (Muslim 572, from Abu Sa'id al-Khudri). Doubt does not invalidate the prayer: one holds to the certain, and the two prostrations of forgetfulness repair the doubt.

Forgetfulness (sahw) itself has two causes: omission (nuqsan) and addition (ziyada). Deliberate acts are excluded: the scholars agree that whoever adds or omits a pillar on purpose invalidates his prayer (Ibn Abd al-Barr, at-Tamhid). The prostration of forgetfulness never repairs a pillar: whoever omitted one and remembers returns to it and performs it; the prostration covers the sunnas, not the pillars (Ibn Rushd, Bidayat al-Mujtahid; al-Mawardi, al-Hawi al-Kabir).

The three sujud as-sahw cases

• Addition by forgetfulness: two prostrations before the salam, the position of the majority after the hadith of Abu Hurayra (Muslim 571).
• Omission by forgetfulness: the Prophet saluted, prostrated twice, then saluted again (al-Bukhari 1224, hadith of Ibn Buhayna): the sujud comes after the salam.
• Doubt: build on the most likely, complete the prayer, then two prostrations (Muslim 572).

The schools detail: the Hanafis place the two prostrations after the salam in all cases, after Thawban: "for every forgetfulness, two prostrations after saluting" (Abu Dawud 1014); the Malikis, Shafi'is and Ahmad place it before the salam for addition and after the salam for omission. Al-Mawardi sets the frame: no disagreement on the validity of the prostration before or after the salam, the dispute bears on what is recommended (al-Hawi al-Kabir); an-Nawawi reports the same from Qadi Iyad (Sharh Sahih Muslim).

The form: two prostrations like ordinary ones. In the majority view they follow the final tashahhud, then one salutes; according to Abu Hanifa and Malik, when they come after the salam one makes the tashahhud then the final salam (Ibn Rushd, Bidayat al-Mujtahid). Whoever forgot the sujud: the prayer stays valid in the majority view, he prostrates if he remembers, even after speaking (Muslim, from Ibn Mas'ud).

The imam carries the forgetfulness of his followers: the hadith "no forgetfulness upon the one praying behind the imam" is reported by ad-Daraqutni and al-Bayhaqi and judged weak by al-Albani (Irwa al-Ghalil). The follower who missed his imam's prostration prostrates after the imam's salam according to Malik, al-Shafi'i and a version of Ahmad (al-Mughni of Ibn Qudama). The one who joined late follows the imam in his prostration then completes what remains, and the schools detail the rest (Bidayat al-Mujtahid).

Excused errors

• The Hanafis: the prostration is due for an obligation left by forgetfulness: the tashahhud, the qunut, the takbirs of the two Eids, loud or silent recitation in its place (ad-Durr al-Mukhtar; Mukhtasar al-Quduri).
• The Malikis: specific sunnas: recitation after the Fatiha, loud or silent recitation in its place, the takbirs, the first tashahhud and its sitting (Hashiyat ad-Dasuqi).
• The Shafi'is: the whole set of the prayer's sunnas (Nihayat al-Muhtaj).

Foreign acts committed out of ignorance are excused: Mu'awiya ibn al-Hakam spoke during the Prophet's prayer, the Prophet taught him without prescribing a prostration (Muslim 537). Deliberate acts break the prayer: the prostration is a mercy for forgetfulness, not a door for willful negligence.