It is narrated from Sayyiduna Abdullah bin Abi Awfa (may Allah be pleased with him) that in the year of Khaybar, we found some donkeys outside the settlement and slaughtered them. Then a proclaimer of the Prophet (ﷺ) announced: "Whatever is in the pots, throw it out." So we overturned the boiling pots. Abu Ishaq says: I mentioned this hadith to Saeed bin Jubair (may Allah have mercy on him), and he said: "Those donkeys used to eat filth."
Hadith Referenceالسنن المأثورة / باب في أكل لحوم الخيل والبغال والحمير / 575
Hadith Takhrijسنن نسائی، الصید والذبائح، باب تحریم اکل لحوم الحمر الاھلیة، رقم: 4339 وقال الالبانی: صحیح، مسند احمد: 143/32، رقم: 19400 وقال الارنوؤط: اسنادہ صحیح علی شرط الشیخین۔