Musnad Ahmad 27:837

'Abd al-Rahman narrated to us, Sulaym ibn Akhdar narrated to us, from 'Ubayd Allah, from Nafi', from Ibn 'Umar, who said: "The Messenger of Allah, peace and blessings of Allah be upon him, allotted in the spoils of war (al-anfal) two shares for the horse, and one share for the man."