Deuteronomy 15:1, 12-15, 18

At the end of every seven years you must cancel debts.

If any of your people—Hebrew men or women—sell themselves to you and serve you six years, in the seventh year you must let them go free. And when you release them, do not send them away empty-handed. Supply them liberally from your flock, your threshing floor and your winepress. Give to them as the LORD your God has blessed you. Remember that you were slaves in Egypt and the LORD your God redeemed you. That is why I give you this command today.

Do not consider it a hardship to set your servant free, because their service to you these six years has been worth twice as much as that of a hired hand. And the LORD your God will bless you in everything you do.