Musnad Ahmad 33:870

Muhammad ibn Ubayd narrated to us, Muhammad ibn Ishaq narrated to us, from Abdullah ibn Abi Najih, from Mujahid, from Jabir ibn Abdullah al-Ansari, who said: There was a man from Banu Udhrah called Abu Madhkur, and he had a Coptic slave whom he emancipated conditionally upon his death (tadbir). He was in need. The Messenger of Allah (peace and blessings of Allah be upon him) said: "If one of you is in need, let him begin with himself." He said: So he ordered him to make use of him, and he sold him to Nu'aym ibn Abdullah al-Nahham al-Adawi for eight hundred dirhams.