The wudoo’ of the Prophet (peace and blessings of Allaah be upon him) was not invalidated by sleep
Question

What is the evidence that sleep invalidates wudoo’? How can we understand the fact that the Prophet (peace and blessings of Allaah be upon him) got up for Fajr prayer after sleeping without doing wudoo’, according to the hadeeth about him praying qiyaam al-layl with Ibn ‘Abbaas (may Allaah be pleased with him)?.
Praise be to Allah.Firstly: 
With regard to the evidence that sleep invalidates wudoo’, this is proven by the hadeeth of Safwaan ibn ‘Assaal (may Allaah be pleased with him) who said: The Messenger of Allaah (peace and blessings of Allaah be upon him) used to command us, if we were travelling, not to take off our khufoof for three days and nights, except in the case of janaabah, but not in the case of stools, urine or sleep. Narrated by al-Tirmidhi, 89; classed as hasan by al-Albaani. So he mentioned sleep as one of the things that invalidate wudoo’. 
In the answer to question no 36889 , we have mentioned the different opinions of the scholars as to whether sleep invalidates wudoo’, and we stated that the correct view is that sleep invalidates wudoo’ if it is deep, but light sleep does not invalidate wudoo’. 
With regard to the hadeeth of Ibn ‘Abbaas referred to by the questioner, it was narrated by al-Bukhaari (698) and Muslim (763) from Ibn ‘Abbaas (may Allaah be pleased with him) who said: I slept in the house of Maymoonah and the Prophet (peace and blessings of Allaah be upon him) was with her that night. He did wudoo’ then he stood to pray, and I stood on his left, but he took hold of me and moved me to his right. Then he prayed thirteen rak’ahs, then he slept until he was breathing deeply, for when he slept he used to breathe deeply. Then the muezzin came to him and he went out and prayed, and he did not do wudoo’. 
The Prophet (peace and blessings of Allaah be upon him) slept, and he got up to pray and did not do wudoo’. The scholars stated that this ruling (that wudoo’ is not invalidated by sleeping) applies only to the Messenger (peace and blessings of Allaah be upon him), because the eyes of the Prophet (peace and blessings of Allaah be upon him) used to sleep but his heart did not, so if he had broken his wudoo’ he would have been aware of it. 
Al-Nawawi said: 
The words “then he lay down and slept until he was breathing deeply, then he got up and prayed and did not do wudoo’” refer to something that applied only to the Prophet (peace and blessings of Allaah be upon him), namely that if he slept lying down, that did not invalidate his wudoo’, because his eyes slept but his heart did not, so if he had broken his wudoo’ he would have been aware of it, unlike other people. End quote. 
Al-Haafiz said: 
The words “he prayed and did not do wudoo’” – the eyes of the Prophet (peace and blessings of Allaah be upon him) slept but his heart did not, so if he had broken his wudoo’ he would have been aware of it. Hence sometimes he did wudoo’ when he got up from sleep, and sometimes he did not. Al-Khattaabi said: His heart was prevented from sleeping so that he would be aware of the Wahy (Revelation) if it came whilst he was sleeping. End quote. 
Al-Bukhaari (3569) narrated from ‘Aa’ishah (may Allaah be pleased with her) that the Messenger of Allaah (peace and blessings of Allaah be upon him) said: “My eyes sleep, but my heart does not.” It was also narrated by Ahmad (7369) from Abu Hurayrah (may Allaah be pleased with him). 
See Silsilat al-Ahaadeeth al-Saheehah by al-Albaani, 696 
Ibn Maajah (474) narrated that ‘Aa’ishah (may Allaah be pleased with her) said: The Messenger of Allaah (peace and blessings of Allaah be upon him) would fall asleep until he was breathing deeply, then he would get up and pray, and he did not do wudoo’. Classed as saheeh by al-Albaani in Saheeh Ibn Maajah. 
Al-Sindi said in Haashiyat Ibn Maajah: 
This refers to the sound that is made by one who sleeps. 
“He would pray and he did not do wudoo’” because his eyes would sleep but his heart did not, as is stated clearly in the books of Saheeh. His sleep did not invalidate his wudoo’ because sleep only invalidates wudoo’ when there is the fear that something may come out of a person without him realizing it, but that does not apply in the case of one whose heart does not sleep. Then he said: The ahaadeeth about the sleep of the Prophet (peace and blessings of Allaah be upon him) should not be mentioned under this heading at all, i.e., the heading of wudoo’ being invalidated by sleep, without explaining that this ruling applied only to him. End quote.