Musannaf Ibn Abi Shayba 28:134

Jarir narrated to us, from Mughira, from Hammad, from Ibrahim, who said: When Magian women and idolaters are taken captive, Islam is presented to them, and they are compelled to it. If they accept Islam, they may be had intercourse with and employed. If they refuse to accept Islam, they may be employed, but they may not be had intercourse with.