Musannaf Ibn Abi Shayba 28:791

Affan narrated to us, he said: Abd al-Wahid ibn Ziyad narrated to us, he said: Hajjaj ibn Artah narrated to us, he said: Abu al-Zubayr narrated to us, from Jabir ibn Abdullah, he said: It was asked how the Messenger of Allah, may Allah bless him and grant him peace, used to do with the khums (one-fifth). He said: He used to equip from it in the way of Allah one man, then another man, then another man.