Numbers 1:47-51

The ancestral tribe of the Levites, however, was not counted along with the others. The LORD had said to Moses: “You must not count the tribe of Levi or include them in the census of the other Israelites. Instead, appoint the Levites to be in charge of the tabernacle of the covenant law—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. 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 approaches it is to be put to death.