Genesis 25:19-21

Now these are the records of the descendants of Isaac, Abraham’s son: Abraham was the father of Isaac. 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].