Numbers 1:50-53

Put the Levites in charge of the Tabernacle of the Covenant, along with all its furnishings and equipment. They must carry the Tabernacle and all its furnishings as you travel, and they must take care of it and camp around it. Whenever it is time for the Tabernacle to move, the Levites will take it down. And when it is time to stop, they will set it up again. But any unauthorized person who goes too near the Tabernacle must be put to death. Each tribe of Israel will camp in a designated area with its own family banner. But the Levites will camp around the Tabernacle of the Covenant to protect the community of Israel from the LORD’s anger. The Levites are responsible to stand guard around the Tabernacle.”