16 Now to Abraham were the undertakings given, and to his seed. He says not, And to seeds, as of a great number; but as of one, he says, And to your seed, which is Christ. 17 Now this I say: The law, which came four hundred and thirty years after, does not put an end to the agreement made before by God, so as to make the undertaking without effect. 18 Because if the heritage is by the law, it is no longer dependent on the word of God; but God gave it to Abraham by his word.
Matthew Henry's Commentary on Galatians 3:16-18
Commentary on Galatians 3:15-18
(Read Galatians 3:15-18)
The covenant God made with Abraham, was not done away by the giving the law to Moses. The covenant was made with Abraham and his Seed. It is still in force; Christ abideth for ever in his person, and his spiritual seed, who are his by faith. By this we learn the difference between the promises of the law and those of the gospel. The promises of the law are made to the person of every man; the promises of the gospel are first made to Christ, then by him to those who are by faith ingrafted into Christ. Rightly to divide the word of truth, a great difference must be put between the promise and the law, as to the inward affections, and the whole practice of life. When the promise is mingled with the law, it is made nothing but the law. Let Christ be always before our eyes, as a sure argument for the defence of faith, against dependence on human righteousness.