‘You are a priest for ever, in the order of Melchizedek.’ Others became priests without any oath, 21 but he became a priest with an oath when God said to him: ‘The Lord has sworn and will not change his mind: “You are a priest for ever.”’ 22 Because of this oath, Jesus has become the guarantor of a better covenant.
23 Now there have been many of those priests, since death prevented them from continuing in office; 24 but because Jesus lives for ever, he has a permanent priesthood. 25 Therefore he is able to save completely those who come to God through him, because he always lives to intercede for them.
26 Such a high priest truly meets our need – one who is holy, blameless, pure, set apart from sinners, exalted above the heavens. 27 Unlike the other high priests, he does not need to offer sacrifices day after day, first for his own sins, and then for the sins of the people. He sacrificed for their sins once for all when he offered himself. 28 For the law appoints as high priests men in all their weakness; but the oath, which came after the law, appointed the Son, who has been made perfect for ever.
Hebrews 7:17,20-28