Numbers 3:10 "So you shall appoint Aaron and his sons that they may keep their priesthood, but the layman who comes near shall be put to death."

Numbers 3:38 Now those who were to camp before the tabernacle eastward, before the tent of meeting toward the sunrise, are Moses and Aaron and his sons, performing the duties of the sanctuary for the obligation of the sons of Israel; but the layman coming near was to be put to death.

Numbers 4:1 Then the LORD spoke to Moses and to Aaron, saying,

Numbers 4:15 "When Aaron and his sons have finished covering the holy objects and all the furnishings of the sanctuary, when the camp is to set out, after that the sons of Kohath shall come to carry them, so that they will not touch the holy objects and die. These are the things in the tent of meeting which the sons of Kohath are to carry.

Numbers 4:19 "But do this to them that they may live and not die when they approach the most holy objects: Aaron and his sons shall go in and assign each of them to his work and to his load; (NASB ©1995)