Exodus 21:2-4

“If you buy a Hebrew slave, he shall serve for six years; but on the seventh he shall go out as a free man without payment. If he comes alone, he shall go out alone; if he is the husband of a wife, then his wife shall go out with him. If his master gives him a wife, and she bears him sons or daughters, the wife and her children shall belong to her master, and he shall go out alone.