Musannaf Ibn Abi Shayba 13:1811

Abu Bakr narrated to us, he said: Ad-Dahhak bin Makhlad narrated to us, from Ibn Jurayj, from ‘Ata’, regarding a man who emancipated one-third of his slave during his terminal illness. He said: It is to be appraised within his one-third [of his estate]. If he had made other bequests, the slave is to work to earn his freedom [to cover the remainder].