Moffatt(i)
16 Now the Promises were made to Abraham and to his offspring; it is not said, 'and to your offsprings' in the plural, but in the singular and to your offspring — which is Christ.
17 My point is this: the Law which arose four hundred and thirty years later does not repeal a will previously ratified by God, so as to cancel the Promise.
18 If the Inheritance is due to law, it ceases to be due to promise. Now it was by a promise that God bestowed it on Abraham.