What breaks the wudu (ablution)

The rule of doubt is stated by the Prophet (may Allah's peace and blessings be upon him):

There is no wudu unless one hears a sound or perceives a smell.al-Bukhari 137

Doubt about passing wind therefore does not break wudu as long as one has no certainty.

What breaks wudu by consensus

• Anything exiting the two passages: urine, stool, wind (Muslim 362).
• Urine or seminal discharge during sleep (madhi, mani).
• Deep extended sleep, or sitting sleep when the seat no longer holds (al-Bukhari 149).
• Loss of consciousness, intoxication, fainting.
• Eating camel meat (Muslim 360).

Points of difference

• Touching one's spouse with desire: Shafi'is, any skin-to-skin contact breaks it; Malikis and Hanbalis, contact with desire; Hanafis, it does not.
• Camel meat: obligatory for Shafi'is and Hanbalis, not for Hanafis, recommended for Malikis.
• Flowing blood (cupping, wound): Hanafis, abundant blood breaks it; the others, no.

Practical note

If one perceives a sound or smell during prayer, one stops and renews wudu; otherwise one ignores the doubt and prays confidently. One suffering a persistent flux (incontinence) performs wudu at the time of each prayer and prays with it, even if the flux appears during the prayer.