Romans 4:13
Besides, the promise that he should possess the world, was not made to Abraham, or to his posterity in consideration of the law, but with regard to the righteousness by faith.
Galatians 3:29
and if you belong to Christ, you are Abraham's offspring, and his heirs by virtue of the promise.
Romans 9:8
that is, the children by natural descent are not thereby the children of God: but the children of the promise are alone considered as his posterity.
Galatians 3:16-18
now to Abraham and his offspring were the promises made. he does not say, "to offsprings," as if he spoke of many; but as speaking of one, "and to thy offspring," which means Christ.