Deuteronomy 15:17
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
More from Deuteronomy 15
At the end of every seven years thou shalt make a release.
And this is the manner of the release: Every creditor that lendeth ought unto his neighbour shall release it; he shall not exact it of his neighbour, or of his brother; because it is called the LORD'S release.
Of a foreigner thou mayest exact it again: but that which is thine with thy brother thine hand shall release;
Save when there shall be no poor among you; for the LORD shall greatly bless thee in the land which the LORD thy God giveth thee for an inheritance to possess
Only if thou carefully hearken unto the voice of the LORD thy God, to observe to do all these commandments which I command thee this day.