Deuteronomy 15:13-17

And when you set him free, you shall not send him away empty-handed.

You shall give generously to him from your flock, your threshing floor, and from your wine vat; you shall give to him as the Lord your God has blessed you.

And you are to remember that you were a slave in the land of Egypt, and the Lord your God redeemed you; therefore I am commanding this of you today.

But it shall come about, if he says to you, ‘I will not leave you,’ because he loves you and your household, since he is doing well with you,

then you shall take an awl and pierce it through his ear into the door, and he shall be your servant permanently. You shall also do the same to your female slave.