Galatians 3:15-20

15 Brothers and sisters, I give an example from daily life: once a person's will has been ratified, no one adds to it or annuls it.
16 Now the promises were made to Abraham and to his offspring; it does not say, "And to offsprings," as of many; but it says, "And to your offspring," that is, to one person, who is Christ.
17 My point is this: the law, which came four hundred thirty years later, does not annul a covenant previously ratified by God, so as to nullify the promise.
18 For if the inheritance comes from the law, it no longer comes from the promise; but God granted it to Abraham through the promise.
19 Why then the law? It was added because of transgressions, until the offspring would come to whom the promise had been made; and it was ordained through angels by a mediator.
20 Now a mediator involves more than one party; but God is one.

Footnotes 6

New Revised Standard Version Bible, copyright 1989, Division of Christian Education of the National Council of the Churches of Christ in the United States of America. Used by permission. All rights reserved.