Musnad Ahmad 27:732

Yahya narrated to us, from Ubaydullah, Nafi’ informed me, from Ibn Umar, that the Messenger of Allah (peace and blessings of Allah be upon him) held a horse race for the trained horses from Al-Hafya’ to Thaniyat al-Wada’. And for those that were not trained, from Thaniyat al-Wada’ to the Mosque of Banu Zurayq.