Exodus 12:14

12:14 This day will become a memorial for you, and you will celebrate it as a festival to the Lord – you will celebrate it perpetually as a lasting ordinance.

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 29:9

29:9 and wrap the sashes around Aaron and his sons and put headbands on them, and so the ministry of priesthood will belong to them by a perpetual ordinance. Thus you are to consecrate Aaron and his sons.

Exodus 40:15

40:15 and anoint them just as you anointed their father, so that they may minister as my priests; their anointing will make them a priesthood that will continue throughout their generations.”