Numbers 1:50, 53

But appoint the Levites over the tabernacle of the testimony, and over all its furnishings, and over all that belongs to it. They are to carry the tabernacle and all its furnishings, and they shall take care of it and shall camp around the tabernacle.

But the Levites shall camp around the tabernacle of the testimony, so that there may be no wrath on the congregation of the people of Israel. And the Levites shall keep guard over the tabernacle of the testimony.”