It is narrated from Sayyiduna Jabir bin Abdullah (may Allah be pleased with him) that on the day of Khaybar, the Messenger of Allah (peace and blessings be upon him) forbade the meat of domestic donkeys and permitted the eating of horse meat.
Lady Asma (may Allah be pleased with her) says: We slaughtered a horse during the time of the Messenger of Allah (peace and blessings be upon him), then we ate its meat.