15 Dear brothers and sisters, here’s an example from everyday life. Just as no one can set aside or amend an irrevocable agreement, so it is in this case.
16 God gave the promises to Abraham and his child. And notice that the Scripture doesn’t say “to his children, ” as if it meant many descendants. Rather, it says “to his child”—and that, of course, means Christ.
17 This is what I am trying to say: The agreement God made with Abraham could not be canceled 430 years later when God gave the law to Moses. God would be breaking his promise.
18 For if the inheritance could be received by keeping the law, then it would not be the result of accepting God’s promise. But God graciously gave it to Abraham as a promise.