Galatians 3:14
And this he did that the blessing given to Abraham might be extended to the Gentiles through their union with Jesus Christ; that so, through our faith, we also might receive the promised gift of the Spirit.
Romans 4:11
Not after, but before. And it was as a sign of this that he received the rite of circumcision-to attest the righteousness due to the faith of an uncircumcised man-in order that he might be the father of all who have faith in God even when uncircumcised, that they also may be regarded by God as righteous;
Galatians 3:7
You see, then, that those whose lives are based on faith are the Sons of Abraham.