Romans 4:13
For the promise made to Abraham and his descendants, that he should own the world, was not conditioned on the law, but on the right standing he had with God through faith.
Galatians 3:29
And if you belong to Christ, then you are real descendants of Abraham, and heirs in accordance with the promise made to him.
Romans 9:8
That is, it is not Abraham's natural descendants who are God's children, but those who are made children by the promise are counted his true descendants.
Galatians 3:16-18
Now the promises were made to Abraham and his descendant. It does not say, "and to your descendants," in the plural, but in the singular, "and to your descendant," that is, Christ.