Numbers 8:20

"Thus did Moses, and Aaron, and all the congregation of the children of Israel, unto the Levites: according unto all that Jehovah commanded Moses touching the Levites, so did the children of Israel unto them. And the Levites purified themselves from sin, and they washed their clothes; and Aaron offered them for a wave-offering before Jehovah; and Aaron made atonement for them to cleanse them. And after that went the Levites in to do their service in the tent of meeting before Aaron, and before his sons: as Jehovah had commanded Moses, concerning the Levites, so did they unto them."

Whatever the scholars may find difficult in the matter of the "waving" of all those Levites, Aaron had no trouble at all with it. The sacred text says that he did it. This is similar to that passage about casting the money "unto the potter" in the house of the Lord (Zechariah 11:13). The critics have been looking for that "potter" for a hundred years without finding him, but Zechariah had no trouble with it, the Holy Scriptures say that "he did it!"