Musannaf Ibn Abi Shayba 13:1557

Abu Bakr narrated to us, he said: Waki’ narrated to us, from Isma’il ibn Abi Khalid, from ‘Amir, from ‘Abdullah regarding a *mukātab* (an enslaved person with a contract of manumission) who died and left behind wealth and free children. He said: He pays what remains of his *kitābah* (contract), and what remains is for his children.