Numbers 8:20
“And Moses, and Aaron, and all the congregation of the children of Israel, did to the Levites according unto all that the Lord commanded Moses concerning the Levites, so did the children of Israel unto them.”
And I have taken the Levites for all the firstborn of the children of Israel.
And I have given the Levites as a gift to Aaron and to his sons from among the children of Israel, to do the service of the children of Israel in the tabernacle of the congregation, and to make an atonement for the children of Israel: that there be no plague among the children of Israel, when the children of Israel come nigh unto the sanctuary.
And Moses, and Aaron, and all the congregation of the children of Israel, did to the Levites according unto all that the Lord commanded Moses concerning the Levites, so did the children of Israel unto them.
And the Levites were purified, and they washed their clothes; and Aaron offered them as an offering before the Lord; and Aaron made an atonement for them to cleanse them.
And after that went the Levites in to do their service in the tabernacle of the congregation before Aaron, and before his sons: as the Lord had commanded Moses concerning the Levites, so did they unto them.
Counter-Arguments
The strongest case that this verse does not belong in this theme.

Related Verses
“So Aaron and his sons did all things which the Lord commanded by the hand of Moses.”
“And Aaron did so; he lighted the lamps thereof over against the candlestick, as the Lord commanded Moses.”
“And Moses said unto the congregation, This is the thing which the Lord commanded to be done.”
“And Moses did as the Lord commanded him; and the assembly was gathered together unto the door of the tabernacle of the congregation.”
“And Moses told it unto Aaron, and to his sons, and unto all the children of Israel.”