It is narrated from Hazrat Ibn Abbas (may Allah be pleased with them both) that the Messenger of Allah (peace and blessings be upon him) said: Wudu is not obligatory upon sleeping in the state of prostration until one lies down on his side; when he lies down on his side, his limbs will become relaxed.

Hazrat Anas (may Allah be pleased with him) narrates that the companions would lower their heads and fall asleep while waiting for the Isha prayer, then they would stand up and perform the prayer without performing ablution again.

Hazrat Ibn Abbas (may Allah be pleased with them) says that the one who sleeps while sitting does not have to perform ablution, but the one who sleeps lying on his side, his ablution is broken.

Ibrahim narrates that the Prophet Muhammad (peace and blessings be upon him) used to fall asleep while in the state of bowing (ruku) and prostration (sajdah), then he would perform prayer but would not perform ablution.

Ibrahim narrates that the Prophet Muhammad (peace and blessings be upon him) slept in the mosque in such a way that the sound of his snoring could be heard. Then he got up and prayed, but did not perform ablution. Then he said that my eyes sleep but my heart does not sleep.

Hazrat Ibn Umar (may Allah be pleased with them both) narrates that the ablution of a person who sleeps while sitting does not break.

Hazrat Shurahbil bin Muslim and Hazrat Muhammad bin Ziyad say that Hazrat Abu Umamah would sit and fall into a deep sleep, then stand up and perform prayer, but he would not perform ablution.

Hazrat Umar says that whoever touches his side should perform ablution.

Ibn Sirin says that I asked Ubaidah about this, so he said that he knows himself better.

Hazrat Ata says that if a person sleeps while in the state of prostration, or standing, or sitting, his ablution is not broken, but if a person sleeps lying on his side, his ablution is broken.