Genesis 25:20-24

and Isaac was forty years old when he took Rebekah, the daughter of Bethuel the Aramean of Paddan-aram, the sister of Laban the Aramean, to be his wife. Isaac prayed to the LORD on behalf of his wife, because she was barren; and the LORD answered him and Rebekah his wife conceived. But the children struggled together within her; and she said, “If it is so, why then am I this way?” So she went to inquire of the LORD. The LORD said to her, “Two nations are in your womb; And two peoples will be separated from your body; And one people shall be stronger than the other; And the older shall serve the younger.” When her days to be delivered were fulfilled, behold, there were twins in her womb.