Hebrews 7:21-25

(For those priests were made without an oath; but this with an oath by him that said unto him, The Lord sware and will not repent, Thou art a priest for ever after the order of Melchisedec:)

By so much was Jesus made a surety of a better testament.

And they truly were many priests, because they were not suffered to continue by reason of death:

But this man, because he continueth ever, hath an unchangeable priesthood.

Wherefore he is able also to save them to the uttermost that come unto God by him, seeing he ever liveth to make intercession for them.