Numbers 8:22

“And after that went the Levites in, etc.] Into the court of the tabernacle, being at the door of it when the above rites and ceremonies of their consecration were performed: to do their service in the tabernacle of the congregation, before Aaron and his sons; in their presence, and by their order, as they should direct them: as the Lord had commanded Moses, so did they unto them; Aaron and his sons did to the then present Levites according to the command of God by Moses; they exactly observed every punctilio of it, and complied with it; and this the sons of Aaron did continually to the sons of the Levites, as Aben Ezra remarks, in all succeeding ages; when the Levites were consecrated to…”

“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…”

“after that: Num 8:15; Ch2 30:15-17, Ch2 30:27, Ch2 31:2, Ch2 35:8-15 as the Lord: Num. 8:5-26 Numbers 8:24”