Genesis 25:21-24

And Isaac prayed to the LORD for his wife, because she was barren. And the LORD granted his prayer, and Rebekah his wife conceived. The children struggled together within her, and she said, “If it is thus, why is this happening to me?” So she went to inquire of the LORD. And the LORD said to her, “Two nations are in your womb, and two peoples from within you shall be divided; the one shall be stronger than the other, the older shall serve the younger.” When her days to give birth were completed, behold, there were twins in her womb.