Sahih Muslim Book 021, Hadith Number 4778.
Chapter : The eating of the flesh of domestic asses is unlawful.
Anas b. Malik reported: When it was the Day of Khaibar a visitor came and said: Messenger of Allah, the asses have been eaten. Then another came and said: Messenger of Allah, the asses are being destroyed. Then Allah's Messenger (may peace be upon him) commanded Abu Talha to make an announcement that Allah and His Messenger have prohibited you (from eating) of the flesh of (domestic) asses, for these are loathsome or impure. He (the narrator) said: The earth in pots were turned over along with what was in them.