Musannaf Ibn Abi Shayba 19:407

Abu Bakr narrated to us, he said: Ghundar narrated to us, from Shu'bah, from al-Hakam and Hammad, regarding the slave who has a free woman under him, and he accuses her of adultery (qadhf). They both said: There is no *li'an* (imprecation) between them, and he is to be flogged.