Albert Barnes Commentary Hebrews 7:18

"For there is a disannulling of a foregoing commandment because of its weakness and unprofitableness" — Hebrews 7:18 (ASV)

For there is verily a disannulling. This means a setting aside. The law that previously existed concerning the priesthood is now abolished, because of the change that has been made in the priesthood .

Of the commandment. This refers to the commandment relating to the office of priest or to the ceremonial rites in general. This does not refer to the moral law, as if it were abolished, for:

1. The apostle's reasoning does not pertain to it; and
2. That law cannot be abolished, as it grows out of the nature of things and must be perpetual and universal.

Going before. This means going before the Christian dispensation and introducing it.

For the weakness and unprofitableness thereof. That is, it was not suited to save man; it did not have power to accomplish what was necessary for human salvation. It fulfilled the purpose for which it was designed—that of introducing a more perfect plan—and then vanished as a matter of course. It did not expiate guilt; it did not give peace to the conscience; it did not produce perfection (Hebrews 7:11), and therefore it gave place to a better system.