Genesis 25:21 in the World English Bible
Isaac entreated the LORD for his wife, because she was barren. The LORD was entreated by him, and Rebekah his wife conceived.
Context
20 And Isaac was forty years old when he took Rebekah to wife, the daughter of Bethuel the Syrian of Padan-aram, the sister to Laban the Syrian.
21 And Isaac intreated the LORD for his wife, because she was barren: and the LORD was intreated of him, and Rebekah his wife conceived.
22 And the children struggled together within her; and she said, If it be so, why am I thus? And she went to enquire of the LORD.