Galatians 3:15-18

(15-18) To take an illustration from purely human relations. A covenant once ratified is binding. It cannot be treated as if it did not exist, neither can fresh clauses be added to it. Now the covenant and promise made to Abraham (by the terms in which it was made) could point to no one but the Messiah. That covenant remained unaffected by the Law, which was four hundred and thirty years subsequent to it in point of date. Law and promise are two totally different and mutually exclusive things. But the covenant with Abraham was given by promise. The Law, therefore, had nothing to do with it.