Exodus 21:6; Deuteronomy 15:17

then his master shall bring him to kGod, and he shall bring him to the door or the doorpost. And his master shall bore his ear through with an awl, and he shall be his slave forever.

17 then you shall take an awl, and put it through his ear into the door, and he shall be your slave1 forever. And to your female slave2 you shall do the same.