In Hebrews 7:20-28 the author explains how Christ serves after the order of Melchizedek showing that Christ serves according to the oath of God (vv. 20-22, cf. Ps. 110:4), that he is not limited by death from continuing in office (23-25), and that thus he is not appointed according to weakness but, having made a sacrifice for sins once and for all, he is the true priest after the order of Melchizedek, appointed as the Son perfected forever.
Hebrews 7:20-28