Romans 9:10

And not only this; but when Rebecca also had conceived by one, even by our father Isaac;

Romans 9:10 points to the moment when Rebekah conceived twins, Jacob and Esau, by Isaac. Even before the twins were born, God knew the characters each would develop. When Rebekah prayed in distress about her difficult pregnancy, God answered her that the elder would serve the younger. He also revealed that her two sons would become two nations, with one greater than the other.