Musnad Ahmad 1167:22

Waki' narrated to us, he said: Hisham ibn 'Urwah narrated to us, from Fatimah bint al-Mundhir, from Asma' bint Abi Bakr, she said: "We slaughtered a horse during the time of the Messenger of Allah, may Allah bless him and grant him peace, and we ate its meat," or "from its meat."