Musannaf Ibn Abi Shayba 19:475

Abu Bakr narrated to us, he said: Waki’ narrated to us, from Sufyan, from Mughira, from al-Haytham ibn Badr, from Harqus, from Ali, that a man had intercourse with his wife’s slave-girl, and he (Ali) averted the prescribed punishment (hadd) from him.