19These are the descendants of Isaac, Abraham’s son: Abraham was the father of Isaac, 20and Isaac was forty years old when he married Rebekah, daughter of Bethuel the Aramean of Paddan-aram, sister of Laban the Aramean. 21Isaac prayed to the Lord for his wife, because she was barren; and the Lord granted his prayer, and his wife Rebekah conceived. 22The children struggled together within her; and she said, “If it is to be this way, why do I live?” So she went to inquire of the Lord.23And the Lord said to her, “Two nations are in your womb, and two peoples born of you shall be divided; the one shall be stronger than the other, the elder shall serve the younger.” 24When her time to give birth was at hand, there were twins in her womb. 25The first came out red, all his body like a hairy mantle; so they named him Esau. 26Afterward his brother came out, with his hand gripping Esau’s heel; so he was named Jacob. Isaac was sixty years old when she bore them. 27When the boys grew up, Esau was a skillful hunter, a man of the field, while Jacob was a quiet man, living in tents. 28Isaac loved Esau, because he was fond of game; but Rebekah loved Jacob. (Genesis 25:19-28, NRSV)
Rebekah was barren, which is interesting because Rebekah means answer to prayer. Because Rebekah was the answer to the prayer of Abraham and Sarah that Isaac would have a wife, and of the servant who went to their homeland to find her. But she was not able to have children, so Isaac prayed and the had twins.
And the twins fought in her womb and she was told that the two sons would become two nations that would be in battle. Not really what you want to hear when you struggled to get this blessing.
But therein is the story, and everything works together for good through God.