God's promise to Abraham still has authority

¹⁵ My Christian friends, I will use an example from our lives. Two people may make an agreement together and they both agree to it properly. If they do that, nobody else can change that agreement. They cannot take away its authority. ¹⁶ In the same way, God promised to bless Abraham and Abraham's descendant. The Bible does not say ‘descendants’. It does not speak about ‘many people’. No, God promised to bless Abraham's descendant. He speaks about one person, and that person is Christ.^{[a] 17} What I mean is this: God made an agreement with Abraham. He promised to bless him. Then, 430 years later, God gave his Law to Moses for the Jewish people. But that Law could not take away the authority of God's agreement with Abraham. It could not stop what God had already promised.