Numbers 3:10; Numbers 3:38

10 Appoint Aaron and his sons to serve as priests; anyone else who approaches the sanctuary is to be put to death.”

38 Moses and Aaron and his sons were to camp to the east of the tabernacle, toward the sunrise, in front of the tent of meeting. They were responsible for the care of the sanctuary on behalf of the Israelites. Anyone else who approached the sanctuary was to be put to death.