Genesis 25:20-26

Isaac was forty years old when he married Rebekah, the daughter of Bethuel the Aramean (Syrian) of Paddan-aram, the sister of Laban the Aramean. Isaac prayed to the LORD for his wife, because she was unable to conceive children; and the LORD granted his prayer and Rebekah his wife conceived [twins]. But the children struggled together within her [kicking and shoving one another]; and she said, “If it is so [that the LORD has heard our prayer], why then am I this way?” So she went to inquire of the LORD [praying for an answer]. The LORD said to her, “[The founders of] two nations are in your womb; And the separation of two nations has begun in your body; The 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. The first came out reddish all over like a hairy garment; and they named him Esau (hairy). Afterward his brother came out, and his hand grasped Esau’s heel, so he was named Jacob (one who grabs by the heel, supplanter). Isaac was sixty years old when Rebekah gave birth to them.