Num 3:38
Moses and Aaron, with the sons of the latter (the priests), were to encamp in front, before the tabernacle, viz., on the eastern side, “as keepers of the charge of the sanctuary for the charge of the children of Israel,” i.e., to attend to everything that was binding upon the children of Israel in relation to the care of the sanctuary, as no stranger was allowed to approach it on pain of death (see Num 1:51).