Hebrews 7:4-6

ECB(i) 4 And observe his greatness, to whom even the patriarch Abraham gave the tithe from the top of the heap. 5 And indeed they of the sons of Levi who take the office of the priesthood have a misvah to take tithes of the people according to the torah - that is, of their brothers, though they come from the loins of Abraham: 6 but whoever was not genealogized was tithed by Abraham and blessed him who had the pre-evangelisms. Genesis 14:20, Numbers 18:21