Numbers 1:47-53
47 The families of the tribe of Levi, however, were not counted along with the others.
48 The Lord had said to Moses:
49 “You must not count the tribe of Levi or include them in the census of the other Israelites.
50 Instead, appoint the Levites to be in charge of the tabernacle of the Testimony—over all its furnishings and everything belonging to it. They are to carry the tabernacle and all its furnishings; they are to take care of it and encamp around it.
51 Whenever the tabernacle is to move, the Levites are to take it down, and whenever the tabernacle is to be set up, the Levites shall do it. Anyone else who goes near it shall be put to death.
52 The Israelites are to set up their tents by divisions, each man in his own camp under his own standard.
53 The Levites, however, are to set up their tents around the tabernacle of the Testimony so that wrath will not fall on the Israelite community. The Levites are to be responsible for the care of the tabernacle of the Testimony.”