Hebrews 8:7

For if that first covenant had been faultless, then should no place have been sought for the second.

The first arrangement was not without flaw, and because of that lack a place had to be found for a second arrangement. The need for something further arose precisely from the fault in what came first, not from any failure in the divine purpose but from the insufficiency of that first covenant itself. The covenant promised to come after would be inward rather than merely outward, with the divine law set within the mind and written upon the heart. By that inner writing its recipients would become God's own people, and He would be their God.