Musnad Ahmad 2:38

Al-Hakam ibn Nafi' narrated to us, Ibn 'Ayyash narrated to us, from Abu Saba' 'Utbah ibn Tamim, from al-Walid ibn 'Amir al-Yazani, from 'Urwah ibn Mughith al-Ansari, from 'Umar ibn al-Khattab, who said: The Prophet, peace and blessings of Allah be upon him, decreed that the owner of the riding animal has more right to its front.