Musnad Ahmad 658:151

'Abd al-Razzaq narrated to us, Ma'mar narrated to us, from 'Asim, from al-Sha'bi, from al-Bara' ibn 'Azib, who said: "The Messenger of Allah, may Allah bless him and grant him peace, forbade us on the day of Khaybar from the meat of domesticated donkeys, both cooked and raw."