Matthew Poole and continuators on Galatians 3:21

21 Is the law then against the promises of God? God forbid , for if there had been a law given which could have given life , verily righteousness should have been by the law .

Though it be thus, yet there is no such opposition betwixt the Law and the Promises, as that either of them make the other useless. Far be it from me (saith the Apostle) to assert any such thing! they are not contrary to one another, but subservient to one another.

For if there had been a Law, which could by our perfect performance of it, have given us a righteousness, wherein we might have stood righteous before God:

Then righteousness should have been by the Law; then men might have hoped to have been justified and accepted of God by me for such obedience; then indeed the Law had been against the promises, they holding forth another righteousness, viz. the Righteousness of God from Faith to Faith.