Musannaf Ibn Abi Shayba 9:1582

Abu Bakr narrated to us, he said: Mu'adh ibn Mu'adh narrated to us, from Ash'ath, from al-Hasan, regarding a man who married a slave woman and a free woman in one contract: He said, "He is separated from the slave woman." Or regarding a man who married two sisters in one contract: He said, "He is separated from both of them."