Genesis 25:21-23

Now, Rebekah was unable to have children, but Isaac pleaded with YAHWEH on behalf of his wife because she was barren—and she did get pregnant, for YAHWEH responded to Isaac’s prayer. During her pregnancy, Rebekah could feel twins thrashing and struggling with each other inside her womb. So she went to inquire of YAHWEH, saying, “Why do I have to live with this?” And YAHWEH answered her, saying, “The two sons in your womb will become two nations, and the two peoples within you will become rivals. One people will become stronger than the other, and the older will serve the younger.”