Exodus 21:2-4

If you buy a Hebrew servant, he shall serve six years; and in the seventh he shall go out free and pay nothing. If he comes in by himself, he shall go out by himself; if he comes in married, then his wife shall go out with him. If his master has given him a wife, and she has borne him sons or daughters, the wife and her children shall be her master’s, and he shall go out by himself.