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. When the tabernacle is to set out, the Levites shall take it down, and when the tabernacle is to be pitched, the Levites shall set it up. And if any outsider comes near, he shall be put to death. The people of Israel shall pitch their tents by their companies, each man in his own camp and each man by his own standard. 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.”