Sahih Muslim
The Book of Games and the Animals which May be Slaughtered and the Aninals that Are to be Eaten (Kitab-us-Said wal-Dhabaih wa ma Yukalu min Al-Hayawan)
Book Number: 021 / Hadith Number: 4769
Sulaiman Shaibini reported: I heard Abdullah b. Abu Aufa say: We were smitten with hunger during the nights of Khaibar. On the Day of Khaibar, we fell upon domestic asses and we slaughtered them, and when our earthen pots boiled with them, the announcer of Allah's Messenger (may peace be upon him) made an annoancement that the earthen pots should be turned over, and nothing should be eaten of the flesh of the domestic asses. Some of the people said that Allah's Messenger (may peace be upon him) had forbidden (the use of this flesh) for one-fifth (due to the State) has not been paid, while others said: He prohibited it for ever.