Musannaf Ibn Abi Shayba 19:474

Abu Bakr narrated to us, he said: Ibn Fudayl narrated to us, from Mughira, who said: A man came to Ibn Mas’ud and said: "I have had intercourse with my wife’s slave girl." He said: "Allah has covered you, so cover yourself." This reached Ali, and he said: "If the one who came to Ibn Umm ‘Abd had come to me, I would have crushed his head with stones."