Numbers 8:20-22 meaning

All of the procedures described in the previous verses were performed by Moses and Aaron and all the congregation of the sons of Israel to the Levites (v. 20). They were obedient to the word of the LORD and did according to all that the Lord had commanded Moses concerning the Levites. This is similar to other reports of obedience found in the book of Numbers (see 1:54, 2:34, 3:16 for examples). So, in complete obedience, what the LORD commanded regarding the Levites' consecration, the sons of Israel did to them.

Not only were the people obedient to the LORD, the Levites, too, purified themselves from sin and washed their clothes (v. 21) as was commanded in verse 6. Also, Aaron presented them as a wave offering before the Lord as commanded in verse 11. The wave offering was a public dedication of service to God. Using the offerings described in verses 8 - 11, Aaron also made atonement for them to cleanse them.

The consecration service was now complete, so after that the Levites went in to perform their service in the tent of meeting before Aaron and before his sons (v. 22). They started their new jobs right away. They had been purified and separated from the rest of the Israelites for the purpose of serving the LORD and the priests. They did just as the Lord had commanded Moses concerning the Levites, so they did to them.

Their obedience to the LORD's command concerning the Levites was complete and exact. They obeyed "to the letter." This is stark contrast to the events that occur in chapters 11 and following.