in the following way: sprinkle them with the water of purification and have them shave their whole bodies and have them wash their clothes. Then they will be ritually clean.
Then they are to take a young bull and the required grain offering of flour mixed with olive oil; and you are to take another bull for the sin offering.
The Levites shall then put their hands on the heads of the two bulls; one is to be offered as a sin offering and the other as a burnt offering, in order to perform the ritual of purification for the Levites.
and I assign the Levites to Aaron and his sons, as a gift from the Israelites, to work in the Tent for the people of Israel and to protect the Israelites from the disaster that would strike them if they came too near the Holy Place."
The Levites purified themselves and washed their clothes, and Aaron dedicated them as a special gift to the LORD. He also performed the ritual of purification for them.
The people did everything the LORD had commanded Moses concerning the Levites. And so the Levites were qualified to work in the Tent under Aaron and his sons.
After that, he may help his fellow Levites in performing their duties in the Tent, but he must not perform any service by himself. This is how you are to regulate the duties of the Levites."