Musnad Ahmad 33:815

'Affan narrated to us, 'Abd al-Wahid narrated to us, al-Hajjaj narrated to us, Abu al-Zubayr narrated to us, he said: Jabir ibn 'Abd Allah was asked, "How did the Messenger of Allah, peace and blessings of Allah be upon him, deal with the *khums* (one-fifth share)?" He said: "He would equip a man from it in the way of Allah, then another man, then another man."