Hebrews 7:23-25

The [former successive line of] priests, on the one hand, existed in greater numbers because they were each prevented by death from continuing [perpetually in office]; but, on the other hand, Jesus holds His priesthood permanently and without change, because He lives on forever. Therefore He is able also to save forever (completely, perfectly, for eternity) those who come to God through Him, since He always lives to intercede and intervene on their behalf [with God].