Numbers 1:47-51

The Levites, however, were not numbered among them by their fathers’ tribe. For the LORD had spoken to Moses, saying, “Only the tribe of Levi you shall not number, nor shall you take their census among the sons of Israel. But you shall appoint the Levites over the tabernacle of the testimony, and over all its furnishings and over all that belongs to it. They shall carry the tabernacle and all its furnishings, and they shall take care of it; they shall also camp around the tabernacle. So when the tabernacle is to set out, the Levites shall take it down; and when the tabernacle encamps, the Levites shall set it up. But the layman who comes near shall be put to death.