Isaac was forty years old when he took Rebekah as wife, the daughter of Bethuel the Syrian of Padan Aram, the sister of Laban the Syrian.
Genesis 25:20
Surrounding context
25:19 This is the genealogy of Isaac, Abraham's son. Abraham begot Isaac.
25:20 Isaac was forty years old when he took Rebekah as wife, the daughter of Bethuel the Syrian of Padan Aram, the sister of Laban the Syrian.
25:21 Now Isaac pleaded with the LORD for his wife, because she was barren; and the LORD granted his plea, and Rebekah his wife conceived.