Galatians 3:16
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.
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 4:28
Now we, brothers, like Isaac, are children born to fulfill the promise.
Hebrews 11:13
These people all died victoriously as a result of their faith, although they did not receive the blessings promised; that is, because they really saw them in the far-off future and welcomed them, and so professed to be only foreigners and strangers here on earth.