Deuteronomy 15:12-18

If one of your own people sells himself to you as a slave, whether it is a Hebrew man or woman, that person will serve you for six years. But in the seventh year you must let the slave go free. When you let slaves go, don’t send them away without anything. Give them some of your flock, your grain, and your wine, giving to them as the LORD has given to you. Remember that you were slaves in Egypt, and the LORD your God saved you. That is why I am commanding this to you today. But if your slave says to you, “I don’t want to leave you,” because he loves you and your family and has a good life with you, stick an awl through his ear into the door; he will be your slave for life. Also do this to a female slave. Do not think of it as a hard thing when you let your slaves go free. After all, they served you six years and did twice the work of a hired person. The LORD your God will bless you in everything you do.