Numbers 1:51-53

51 "When the holy tent must be moved, the Levites must take it down. And when the tent must be set up, the Levites must do it. Anyone else who goes near it will be put to death.

52 "The people of Israel must set up their tents by companies. All of them must be in their own camps under their own flags.

53 "But the Levites must set up their tents around the holy tent where the tablets of the covenant are kept. Then my anger will not fall on the community of Israel. The Levites will be held accountable for taking care of the tent."