Exodus 21:4

The third case. If the master marries a slave to one of his female slaves, the wife remains her master's slave as she was before, and does not go free with her husband. If she has borne him children, the remain in servitude with their mother. At this early time, children's relationship to their mother was held to be closer and more binding than that to their father.

give him for the slave would not have the right to choose a wife for himself.