Hebrews 7:21-24

(for they indeed became priests without an oath, but He with an oath through the One who said to Him, “THE LORD HAS SWORN AND WILL NOT CHANGE HIS MIND, ‘YOU ARE A PRIEST FOREVER’ ”); so much the more also Jesus has become the guarantee of a better covenant. The former priests, on the one hand, existed in greater numbers because they were prevented by death from continuing, but Jesus, on the other hand, because He continues forever, holds His priesthood permanently.