Jamieson, Fausset and Brown on Hebrews 7:16

16. carnal ... endless--mutually contrasted. As "form" and "power" are opposed, 2Ti 3:5; so here "the law" and "power," compare Ro 8:3, "The law was weak through the flesh"; and He 7:18, "weakness." "The law" is here not the law in general, but the statute as to the priesthood. "Carnal," as being only outward and temporary, is contrasted with "endless," or, as Greek, "indissoluble." Commandments is contrasted with "life." The law can give a commandment, but it cannot give life (He 7:19). But our High Priest's inherent "power," now in heaven, has in Him "life for ever"; He 9:14, "through the eternal Spirit"; He 7:25, "able ... ever liveth" (Joh 5:26). It is in the power of His resurrection life, not of His earthly life, that Christ officiates as a Priest.