Exodus 28:1

The Clothing of the Priests

28:1 “And you, bring near to you your brother Aaron and his sons with him from among the Israelites, so that they may minister as my priests – Aaron, Nadab and Abihu, Eleazar and Ithamar, Aaron’s sons.

Numbers 16:5

16:5 Then he said to Korah and to all his company, “In the morning the Lord will make known who are his, and who is holy. He will cause that person to approach him; the person he has chosen he will cause to approach him.

Numbers 16:40

16:40 It was a memorial for the Israelites, that no outsider who is not a descendant of Aaron should approach to burn incense before the Lord, that he might not become like Korah and his company – just as the Lord had spoken by the authority of Moses.

Numbers 18:7

18:7 But you and your sons with you are responsible for your priestly duties, for everything at the altar and within the curtain. And you must serve. I give you the priesthood as a gift for service; but the unauthorized person who approaches must be put to death.”