Hebrews 7:15-17

And this becomes even more evident if another priest arises in the likeness of Melchizedek, [Ps 110:4] who has become a priest, not on the basis of a physical and legal requirement in the Law [concerning his ancestry as a descendant of Levi], but on the basis of the power of an indestructible and endless life. For it is attested [by God] of Him, “YOU (Christ) ARE A PRIEST FOREVER ACCORDING TO THE ORDER OF MELCHIZEDEK.” [Ps 110:4]