Musannaf Ibn Abi Shayba 28:1029

Abdullah ibn Numayr narrated to us, he said: Ubaydullah ibn Umar narrated to us, from Nafi’, from Ibn Umar, who said: The Messenger of Allah (may Allah bless him and grant him peace) exercised the horses (for racing). He would send those that had been exercised from al-Hafya’ to Thaniyat al-Wada’. And those that had not been exercised (he would send) from Thaniyat al-Wada’ to the mosque of Banu Zurayq.