Exodus 21:6

21:6 then his master must bring him to the judges, and he will bring him to the door or the doorposts, and his master will pierce his ear with an awl, and he shall serve him forever.

Exodus 31:17

31:17 It is a sign between me and the Israelites forever; for in six days the Lord made the heavens and the earth, and on the seventh day he rested and was refreshed.’”