Sayyiduna Ibn Abbas (may Allah be pleased with them both) said: "On the day of Khaybar, the Messenger of Allah (peace and blessings be upon him) forbade the meat of domestic donkeys, having intercourse with pregnant (captive women) until they give birth to what is in their wombs, eating any predatory animal with fangs, selling the spoils of war before they are distributed, and killing children."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 11021