Numbers 1:51-53

51 When it's time to move The Dwelling, the Levites will take it down, and when it's time to set it up, the Levites will do it. Anyone else who even goes near it will be put to death.

52 "The rest of the People of Israel will set up their tents in companies, every man in his own camp under its own flag.

53 But the Levites will set up camp around The Dwelling of The Testimony so that wrath will not fall on the community of Israel. The Levites are responsible for the security of The Dwelling of The Testimony."