Exodus 21:9-11

Living Bible

⁹ And if he arranges an engagement between a Hebrew slave girl and his son, then he may no longer treat her as a slave girl, but must treat her as a daughter. ¹⁰ If he himself marries her and then takes another wife, he may not reduce her food or clothing, or fail to sleep with her as his wife. ¹¹ If he fails in any of these three things, then she may leave freely without any payment.