16:40 It was a memorial for the Israelites, that no outsider who is not a descendant of 1 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 2 of Moses.
Numbers 16:46-48
16:46 Then Moses said to Aaron, “Take the censer, put burning coals from the altar in it, place incense on it, and go quickly into the assembly and make atonement for them, for wrath has gone out from the Lord – the plague has begun!”
16:47 So Aaron did 3 as Moses commanded 4 and ran into the middle of the assembly, where the plague was just beginning among the people. So he placed incense on the coals and made atonement for the people.
16:48 He stood between the dead and the living, and the plague was stopped.
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.”