Romans 4:2-5

For if Abraham was justified by works, he hath whereof to glory; but not toward God. For what saith the scripture? And Abraham believed God, and it was reckoned unto him for righteousness. Now to him that worketh, the reward is not reckoned as of grace, but as of debt. But to him that worketh not, but believeth on him that justifieth the ungodly, his faith is reckoned for righteousness.