Adam Clarke on Hebrews 7:16

Who is made - Appointed to this high office by God himself, not succeeding one that was disabled or dead, according to that law or ordinance directed to weak and perishing men, who could not continue by reason of death.

This is probably all that the apostle intends by the words carnal commandment, εντολης σαρκικης· for carnal does not always mean sinful or corrupt, but feeble, frail, or what may be said of or concerning man in his present dying condition.

But after the power of an endless life - Not dying, or ceasing through weakness to be a priest; but properly immortal himself, and having the power to confer life and immortality on others. He ever lives, as Priest, to make intercession for men; and they who believe on him shall never perish, but have everlasting life.