Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) said: On the day of Khaybar, the Companions of the Messenger of Allah (peace and blessings be upon him) came upon domestic donkeys and cooked their meat. Then the Messenger of Allah (peace and blessings be upon him) ordered that the cooking pots be overturned, and on that day he declared their meat unlawful.
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 11620