Hebrews 7:5-7

Thomson(i) 5 The Levites indeed who receive the priesthood have according to law a commandment to tithe the people, that is their own brethren descended from the loins of Abraham; 6 but he who was not of their pedigree received tithes of Abraham, and blessed him who had the promises. 7 Now, beyond all dispute, the inferior is blessed by the superior.