Musannaf Ibn Abi Shaybah

Hazrat Auf (may Allah have mercy on him) narrates that a man named Hammam bin Umair from the tribe of Banu Taymullah had two real sisters (as wife or slave-girl) during the period of ignorance. And he had not separated from either of them. During the caliphate of Hazrat Umar (may Allah be pleased with him), his case was presented before Hazrat Umar (may Allah be pleased with him), so he sent him a message saying, "Choose one of the two, and by Allah, if you go to the other, I will strike your head."

Hasan (may Allah have mercy on him) says that if a person accepts Islam and he has two women (as wife or slave-girl), then if he wishes, he may keep the first one.

Hazrat Dailami (may Allah have mercy on him) says that I came to the presence of the Prophet ﷺ, and at that time, I had two real sisters in my marriage, whom I had married during the period of ignorance. The Prophet ﷺ said to me, "When you return, divorce one of them."