Exodus 21:2-6

“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. But if the slave plainly says, ‘I love my master, my wife and my children; I will not go out as a free man,’ then his master shall bring him to God, then he shall bring him to the door or the doorpost. And his master shall pierce his ear with an awl; and he shall serve him permanently.