Musannaf Ibn Abi Shayba 13:611

Abu Bakr narrated to us, he said: Waki’ narrated to us, from ‘Ali ibn Mubarak, from Yahya, from ‘Ikrimah, from Ibn ‘Abbas, he said: The prescribed punishment (hadd) for the mukatab (a slave who has a contract of manumission) is the prescribed punishment for the slave.