Musannaf Ibn Abi Shayba 16:102

Abu Bakr narrated to us, he said: Abu Usamah narrated to us, from Abd al-Rahman ibn Yazid ibn Jabir, he said: Al-Qasim and Makhul informed us, from Abu Umamah, that the Messenger of Allah (may Allah bless him and grant him peace) forbade on the day of Khaybar the eating of the domestic donkey.