John Gill Commentary Hebrews 7:24

"but he, because he abideth for ever, hath his priesthood unchangeable." — Hebrews 7:24 (ASV)

But this man, because he continues ever
Though he died, death did not forbid him to continue, as it does other men; he was not forced to die, he died voluntarily; and he continued but for a small time under the power of death; besides, his death was a branch of his priestly office:

so that he not only continued in his divine nature, which still had the human nature in union with it, but he continued in his office as a priest, and quickly rose from the dead; and the virtue of his sacrifice always remains, and he himself ever lives as an intercessor: wherefore he

has an unchangeable priesthood ;
which will never be antiquated, and give place to another; nor does it, or ever will it pass from him to another, for it is needless, seeing he lives, and no other is sufficient for it; and it would be injustice to pass it to another; the glory of it is due to him; and this is matter of comfort to the saints, that he sits a priest upon his throne, and that his priesthood always continues.