Majza'ah relates from his father, Sayyiduna Zahir bin al-Aswad al-Aslami (may Allah be pleased with him) (he was among those who gave the pledge under the tree at the Pledge of Ridwan), that he said: I was kindling fire under the cooking pots of donkey meat (or he said: (taking the meat out) of the pots) when suddenly the caller of the Messenger of Allah (peace and blessings be upon him) called out: "Allah Almighty forbids you the meat of donkeys."
Hadith Referenceالمعجم الكبير للطبراني / باب الزاي / 5292