Hebrews 8:7 - Matthew Poole's English Annotations on the Holy Bible

This proves the gospel covenant better than the Mosaical, for if it had not, there would have been no second. For if that first covenant had been faultless: that first covenant, of which Moses was the mediator, as to the administration of it, (as to the matter of it, it was the same from Adam throughout all ages), was faulty; not because God made it, though it was a less perfect good than what succeeded it; it was able to save those who would rightly use it, and come unto Christ by it, Galatians 3:24; but accidentally, by reason of the priests faults, and people's sinfulness, it became wholly ineffectual to them for saving them; therefore the blame and fault of it is charged on them, Hebrews 8:8. Then should no place have been sought for the second: the question here is vehemently assertive; if that covenant in its Mosaical administration had reached effectually its end, brought all that were under it to Christ, to be saved by him, no place nor room was there, that then being so perfect, for another to succeed it, God would have rested there; but his excellent wisdom and counsel determined to put in being the second, and to set it in the place of the first, that was faulty, and which was to be abrogated by it, Galatians 3:21.