Numbers 3:9

And thou shalt give the Levites unto Aaron and to his sons,.... To be their ministers and servants:they [are] wholly given unto him out of the children of Israel: even all of them entirely, none excepted; the whole tribe which were not in the priestly office; those were separated from the rest of the tribes of Israel, and appointed for the service of the priests: or they were "given, given" ; which is repeated not only to show that they were wholly given, as we render it, but to denote the certainty of it, that they were really given; and especially to declare the freeness of the gift; the priests had them as free gifts, nor did they pay them any thing for, their service; they were maintained another way, namely, by the tithes of the people; and indeed the priests received a tithe out of the tithe of the Levites; so far were they from contributing any thing to their support, or in consideration of the service they did them.