It is narrated from Sayyiduna Salamah that a man asked the Prophet (peace and blessings be upon him) what is the ruling if a man has relations with his wife's slave woman. The Prophet (peace and blessings be upon him) said: If he forced the slave woman into this act, then she will become free and the man will be liable to pay her the equivalent of a dowry. And if this act was done with her consent, then she will remain his slave woman, but the man will still have to pay the equivalent of a dowry.