Numbers 8:15

“And after that shall the Levites go in, etc.] Not into the sanctuary, where only the priests entered, much less into the most holy place, where only the high priest went, and that but once a year, in neither of which places the Levites had anything to do, but into the court of the tabernacle: to do the service of the tabernacle of the congregation: to watch there, and to assist the priests at the altar of burnt offering, to take down the tabernacle and bear the vessels of it, and set it up, as occasion required: and thou shalt cleanse them, and offer them [for] an offering; cleanse them by sprinkling the water of purifying on them, and offer them by waving them as before; and indeed this is…”

“after that, shall the Levites go in to do the service of the tabernacle of the congregation--into the court, to assist the priests; and at removal into the tabernacle--that is, into the door of it--to receive the covered furniture.”

“The Levites could only undertake their duties Numbers 3:0; Numbers 4:0 after the formal exchange of the Levites for the first-born Numbers 3:44-51. The distinction between the “consecration” of the priests Leviticus 8:0 and the less solemn “purification” Numbers 8:21 of the Levites is marked. These rites of purification are similar to those incumbent on the priests of Egypt. Numbers 8:7 Water of purifying - literally, “sin water:” i. e. water to cleanse from sin; no doubt taken from the laver of the sanctuary, which was used by the priests for purification before they went into the tabernacle to minister (compare Numbers 5:17; Exodus 30:18 ff). The “sprinkling” of so large a body of men…”

“Go in - Into the court, where they were to wait upon the priests at the altar of burnt - offering; and, at present, into the tabernacle, to take it down and set it up. Numbers 8:19”

“go in: Num 8:11, Num 3:23-37, 4:3-32; 1Chr. 23:1-32, 25:1-26:32 and offer: Num 8:11, Num 8:13, Num 3:12 Numbers 8:16”