Musnad Ahmad 31:935

Waki’ narrated to us, from Yunus, Abu al-Wadak Jabr ibn Nawf narrated to us, from Abu Sa’id, who said: We obtained donkeys on the day of Khaybar, and the cooking pots were boiling with them. The Prophet, peace and blessings of Allah be upon him, said: "What is this?" We said: Donkeys that we have obtained. He said: "Are they wild or domestic?" We said: No, rather they are domestic. He said: "Overturn them [the pots]." He said: So we overturned them.