Musannaf Ibn Abi Shayba 13:1566

Abu Bakr narrated to us, he said: Humayd ibn Abd al-Rahman narrated to us, from Hasan ibn Salih, from Ibn Abi Najih, from Mujahid, who said: If a man emancipates a slave and he (the slave) has wealth, then the wealth of the slave belongs to the slave.