Deuteronomy 15:15 (KJV)

And when thou sendest him out free from thee, thou shalt not let him go away empty:

Thou shalt furnish him liberally out of thy flock, and out of thy floor, and out of thy winepress: of that wherewith the Lord 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 the Lord thy God redeemed thee: therefore I command thee this thing to day.

And it shall be, if he say unto thee, I will not go away from thee; because he loveth thee and thine house, because he is well with thee;

Then thou shalt take an aul, and thrust it through his ear unto the door, and he shall be thy servant for ever. And also unto thy maidservant thou shalt do likewise.