Musnad Ahmad 5:566

Abdullah narrated to us, Abu Khaythama narrated to me, Hashim ibn al-Qasim narrated to us. Abu Abd al-Rahman said: And Abdullah ibn Abi Ziyad narrated to me, Abu Dawud narrated to us. Both said: Warqa’ narrated to us, from Abd al-A’la, from Abu Jamila, from Ali, who said: "The Messenger of Allah, peace and blessings of Allah be upon him, was cupped, and he commanded me, so I gave the cupper his wage."