Musannaf Ibn Abi Shayba 13:3148

Abu Bakr narrated to us, he said: Zayd ibn al-Hubab narrated to us, from Ibn Abi Dhi'b, from al-Zuhri, regarding a man who owed a debt to his slave, then he (the master) died while he (the slave) had a debt upon him. He said: He strives to pay it off.