Musnad Ahmad 5:238

'Affan and Ishaq ibn 'Isa narrated to us, they said: Hammad ibn Salamah narrated to us, from al-Hajjaj, from al-Hakam, from Maymun ibn Abi Shabib, from 'Ali, who said: The Messenger of Allah, peace and blessings of Allah be upon him, gifted me two young slave brothers. I sold one of them. The Messenger of Allah, peace and blessings of Allah be upon him, said: "What did the two young slaves do?" I said: I sold one of them. The Messenger of Allah, peace and blessings of Allah be upon him, said: "Return him."