Numbers 1:51-53

⁵¹and when the tabernacle setteth forward, the Levites shall take it down; and when the tabernacle encampeth, the Levites shall set it up; and the stranger that cometh near shall be put to death.

⁵²And the children of Israel shall encamp every man in his camp, and every man by his own standard, according to their hosts;

⁵³but the Levites shall encamp round about the tabernacle of testimony, that there come not wrath upon the assembly of the children of Israel; and the Levites shall keep the charge of the tabernacle of testimony.