Hebrews 7:5-10

5Now the law commands the sons of Levi who become priests to collect a tenth from the people—that is, from their brothers—though they too are descended from Abraham. 6But Melchizedek, who did not trace his descent from Levi, collected a tenth from Abraham and blessed him who had the promises. 7And indisputably, the lesser is blessed by the greater.

8In the case of the Levites, mortal men collect the tenth; but in the case of Melchizedek, it is affirmed that he lives on. 9And so to speak, Levi, who collects the tenth, paid the tenth through Abraham. 10For when Melchizedek met Abraham, Levi was still in the loin of his ancestor.