Musannaf Ibn Abi Shayba 19:404

Abu Bakr narrated to us, he said: Hafs narrated to us, from Ash'ath, from al-Hakam and Hammad, from Ibrahim, regarding the slave woman who is under a free man, and he accuses her (of adultery): He said: The prescribed punishment (hadd) is not inflicted upon her, and he does not perform the imprecation (li'an).