Numbers 1:51-53

51 “And when the Dwelling Place is to go forward, the Lĕwites take it down. And when the Dwelling Place is to be set up, the Lĕwites set it up. And the stranger who comes near is put to death.

52 And the children of Yisra’ĕl shall pitch their tents, everyone by his own camp, everyone by his own banner, according to their divisions,”

53 but let the Lĕwites camp around the Dwelling Place of the Witness, so that there be no wrath on the congregation of the children of Yisra’ĕl. And the Lĕwites shall guard the duty of the Dwelling Place of the Witness.”