Romans 4:3

For what saith the scripture? [Genesis 15:6] And Abraham believed God, and it was reckoned unto him for righteousness. [Now, of course, Abraham was some way justified. If he was justified by works, as you Jews suppose, he has ground for glorying toward God, for he can claim his justification from God as a debt due to him; but we hear of no such glorying toward God, and hence he was not justified by works. On the contrary, we hear that he was justified by faith, for the Scripture says that he believed God and his belief was counted unto him for righteousness.]