Musannaf Ibn Abi Shayba 19:487

Abu Bakr narrated to us, he said: Isa bin Yunus narrated to us, from Ibn Abi Arubah, from Qatadah, from Raja, from Qabisah bin Dhu'ayb, that a man had intercourse with his slave woman while she had a husband. Umar bin al-Khattab struck him one hundred [lashes] as a deterrent.