Genesis 25:20-26

and Isaac was forty years old when he took Rebekah, the daughter of Bethuel the Syrian of Paddan-aram, the sister of Laban the Syrian, to be his wife. And Isaac entreated Jehovah for his wife, because she was barren: and Jehovah was entreated of him, and Rebekah his wife conceived. And the children struggled together within her; and she said, If it be so, wherefore do I live? And she went to inquire of Jehovah. And Jehovah said unto her, Two nations are in thy womb, And two peoples shall be separated from thy bowels: And the one people shall be stronger than the other people; And the elder shall serve the younger. And when her days to be delivered were fulfilled, behold, there were twins in her womb. And the first came forth red, all over like a hairy garment; and they called his name Esau. And after that came forth his brother, and his hand had hold on Esau’s heel; and his name was called Jacob: and Isaac was threescore years old when she bare them.