Deuteronomy 15:1, 12-15, 18

At the end of every seven years thou shalt make a release.

If thy brother, a Hebrew man, or a Hebrew woman, be sold unto thee, and serve thee six years; then in the seventh year thou shalt let him go free from thee. And when thou lettest him go free from thee, thou shalt not let him go empty: thou shalt furnish him liberally out of thy flock, and out of thy threshing-floor, and out of thy winepress; as Jehovah thy God hath blessed thee thou shalt give unto him. And thou shalt remember that thou wast a bondman in the land of Egypt, and Jehovah thy God redeemed thee: therefore I command thee this thing to-day.

It shall not seem hard unto thee, when thou lettest him go free from thee; for to the double of the hire of a hireling hath he served thee six years: and Jehovah thy God will bless thee in all that thou doest.