The Levites: Given to Aaron and Sons
Source: TTT
Numbers 3:9
Assign the Levites to Aaron and his sons; they have been given exclusively to him from among the Israelites.
Numbers 8:19
And I have given the Levites as a gift to Aaron and his sons from among the Israelites, to perform the service for the Israelites at the Tent of Meeting and to make atonement on their behalf, so that no plague will come against the Israelites when they approach the sanctuary.”