Galatians 3:16-18

3:16 Now the promises were spoken to Abraham and to his descendant. Scripture does not say, “and to the descendants,” referring to many, but “and to your descendant,” referring to one, who is Christ. 3:17 What I am saying is this: The law that came four hundred thirty years later does not cancel a covenant previously ratified by God, so as to invalidate the promise. 3:18 For if the inheritance is based on the law, it is no longer based on the promise, but God graciously gave it to Abraham through the promise.

Galatians 3:29

3:29 And if you belong to Christ, then you are Abraham’s descendants, heirs according to the promise.