al-Musayyab, that he used to sleep repeatedly while lying down, waiting for the prayer, then he would pray without repeating his wudu'. Perhaps they held the view that sleep is not a hadath (event of impurity) in itself, and that the hadath is a matter of doubt, thus certainty cannot be removed by doubt. For our part, we have the statement of Safwan ibn Assal: "but [he allowed them for] excrement, urine, and sleep." We have already mentioned that it is authentic. 'Ali, may Allah be pleased with him, narrated from the Prophet (peace and blessings of Allah be upon him) that he said: "The eyes are the binding of the anus (4); whoever sleeps, let him perform wudu'." It was reported by Abu Dawud and Ibn Majah (5). Furthermore, sleep is a circumstance conducive to a hadath, so it is placed in its stead, just as the contact of the two circumcised parts is placed in the stead of emission in terms of the obligation of ghusl (major ritual bathing).

Section: Sleep is divided into three categories: The sleep of one lying down, which nullifies wudu' whether it is little or much, according to the opinion of everyone who holds that sleep nullifies it. The second is the sleep of one sitting; if it is much, it nullifies it, according to one [established] report, but if it is little, it does not nullify it. This is the opinion of Hammad, al-Hakam, Malik, al-Thawri, and the People of Opinion (Ashab al-Ra'y). Al-Shafi'i said: It does not nullify it even if it is much, provided that the sitting person is firmly seated (6), with his place of potential hadath (the buttocks) pressing against the ground; due to what Anas reported, saying: "The companions of the Messenger of Allah (peace and blessings of Allah be upon him) used to sleep, then stand up and pray without performing wudu' (7)." Al-Tirmidhi said: This is a hasan sahih (sound and authentic) hadith. In another wording, he said: "The companions of the Prophet (peace and blessings of Allah be upon him) would wait for the late night prayer (al-'isha' al-akhira) until their heads would nod, then they would pray without performing wudu' (8)." This is an indication concerning all of them, and through it, the generality of the first two hadiths is specified. Also, because he is guarding against the exit of a hadath, his wudu' is not nullified, just as if his sleep were little. We have the generality of the first two hadiths, and we only specified them in the case of little sleep due to the hadith of Anas, and it contains no specification regarding a large amount.