Hazrat Aisha (may Allah be pleased with her) narrates that the Prophet (peace and blessings be upon him) used to sleep until the sound of his snoring could be heard, then he would get up and perform prayer without performing ablution.

Hazrat Hakam and Hazrat Hammad state that ablution is not nullified until the side touches the ground.

Ibrahim says that sleeping while standing or sitting does not break wudu; wudu is broken by lying down on one's side.

Hazrat Ibn Abbas (may Allah be pleased with them) says that the ablution of every sleeping person is broken, except for the one who sleeps by bowing his head once or twice; his ablution is not broken.

Hazrat Ibn Abbas (may Allah be pleased with them both) narrates that once I went to my aunt, Hazrat Maymunah, the Mother of the Believers. That night, the Messenger of Allah (peace and blessings be upon him) was also there. He (peace be upon him) got up at night to pray, then slept in such a way that I could even hear the sound of his breathing. Then Hazrat Bilal came to inform about the prayer, so the Messenger of Allah (peace and blessings be upon him) went for the prayer, even though he neither performed ablution nor touched water.

Abdullah narrates that sometimes the Prophet Muhammad (peace and blessings be upon him) would fall asleep in the state of prostration to such an extent that we could hear the sound of his breathing, from which we would know that he was asleep. Then he (peace and blessings be upon him) would wake up and continue the prayer.

Hazrat Abu Musa used to sleep among the people in such a way that the sound of his snoring could be heard. When he was awakened, he would say, "Did you hear the sound of my ablution breaking?" People would say, "No," so he would get up and start the prayer.

Hazrat Abu Huraira said: Whoever becomes entitled to sleep, his ablution is broken. Jariri says that we asked about the entitlement to sleep, and we were told that it means placing one's side on the ground.

Hazrat Tawus was asked about sleeping while sitting, so he replied: "This is equivalent to sleeping while reclining; this breaks the ablution."

Hazrat Ikrimah says that sleeping while sitting means sleeping while leaning against something, and sleeping in this manner also breaks wudu.