Numbers 18:1-7
The work of the priests and the Levites
1 The Lord said to Aaron, ‘You and your sons and your family will be guilty for any wrong thing that happens in my Holy Tent. You and your sons will be guilty for any wrong thing that a priest does. 2 Bring the people of your tribe, the Levites, to the Tent of Meeting. 3 They must take care of the Tent of Meeting on your behalf. You must tell them what they should do. They must not go near anything that is inside God's Holy Place or the altar. If they do, they will die, and you will die too. 4 The Levites must work with you as they take care of the Tent of Meeting. No other people have authority to come near you as you work there.
5 You must take care of God's Holy Place and the altar. Then I will not be angry with the Israelites again. 6 I have chosen your family, the Levites, from among the other Israelite tribes. They are the Lord's gift to you, to help you take care of the Tent of Meeting. 7 But only you, Aaron, and your sons will serve me as priests. You will work at the altar and in the Holy Place behind the curtain. I have chosen you to serve me as my priests. That is my gift to you. Any other person who comes near the Holy Place must die.’