And He gave him the covenant of circumcision; and so Abraham was the father of Isaac, and circumcised him on the eighth day; and Isaac was the father of Jacob, and Jacob of the twelve patriarchs.
Brothers, I speak in human terms: even though it is only a man’s covenant, yet when it has been ratified, no one sets it aside or adds conditions to it.
And what I am saying is this: the Law, which came 430 years later, does not invalidate a covenant previously ratified by God, so as to abolish the promise.