Matthew Poole and continuators on Galatians 3:10

10 For as many as are of the works of the law are under the curse, for it is written, Cursed is every one that continueth not in all things which are written in the book of the law to do them .

To be under the Law, is under the Covenant of works, or under the expectation of Life and Salvation only from obedience to the works of the Law. These (he saith) are under the curse, the reason of which the Apostle gives us, Rom. 8.3. Because it is made weak through our flesh, could man perfectly fulfil the Law, he might expect life from it, and salvation from his obedience to it; but the Law curseth him that continueth not in all that is written in it; If a man keepeth the whole Law, if he offends but in one point, he is guilty of all; and as liable to the wrath of God, as if he had broken it in many things▪ Hence it necessarily followeth, if no man can keep the Law of God perfectly, that all under the Law must be under the curse, and consequently cannot be blessed in faithful Abraham.

The Argument is this, Those that are under a curse, cannot be under the blessing of Justification. But those that are under the Law are under the curse. This he proves out of the Law, Deut. 27.26. where those are pronounced Cursed, who continue not in all things written in the book of the Law to do them.