Numbers 3:9

3:9 You are to assign the Levites to Aaron and his sons; they will be assigned exclusively to him out of all the Israelites.

Numbers 3:46

3:46 And for the redemption of the 273 firstborn males of the Israelites who exceed the number of the Levites,

3:49 So Moses took the redemption money from those who were in excess of those redeemed by the Levites.

7:6 So Moses accepted the carts and the oxen and gave them to the Levites.

8:9 You are to bring the Levites before the tent of meeting and assemble the entire community of the Israelites.

8:13 You are to have the Levites stand before Aaron and his sons, and then offer them as a wave offering to the Lord.