Musannaf Ibn Abi Shayba 13:708

Abu Bakr narrated to us, he said: Ibn ‘Uyaynah narrated to us, from ‘Amr, from Jabir, that a man declared his slave to be free after his death (tadbir). The Messenger of Allah (may Allah bless him and grant him peace) sold him to Ibn al-Nahham. He was a Coptic slave who died last year during the governorship of Ibn al-Zubayr.