Deuteronomy 15:12

“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 a brother of yours becomes so poor with regard to you that he sells himself to you, you shall not subject him to a slave’s service.

“You shall not oppress a hired person who is afflicted and needy, whether he is one of your brothers or one of your sojourners who is in your land within your gates.

“At the end of seven years each of you shall let his Hebrew brother go who has been sold to you and has served you six years, and you shall let him go to be free from you; but your fathers did not obey Me or incline their ear to Me.