Heb 7:1-3
"For this Melchizedek, king of Salem, priest of the Most High God, met Abraham returning from the slaughter of the kings and blessed him, and to him Abraham apportioned a tenth part of everything. He is first, by translation of his name, king of righteousness, and then also king of Salem, that is, king of peace. He is without father or mother or genealogy, having neither beginning of days nor end of life, but resembling the Son of God he continues a priest forever."
Melchizedek (Gen 14) is presented as a type of Christ: (1) king of righteousness and peace; (2) without recorded genealogy — a type of the eternal; (3) received a tithe from Abraham — superior to the Levitical priesthood descending from Abraham. The argument: if Abraham paid tithes to Melchizedek, then Melchizedek’s priesthood is superior to the Levitical.