But he whose descent is not counted from them— This sufficiently explains what is meant in the preceding verses by Melchisedec's being said to be without father or mother: his descent or genealogy was not derived either from Abraham's line, or from any other; but, such as he was, he exercised the priestly office, and blessed him that had the promises.
Related Commentaries of Hebrews 7:6
Hebrews 7:6
6 But he whose descent is not counted from them received tithes of Abraham, and blessed him that had the promises.