Romans 9:7-9

Revised Standard Version Catholic Edition

⁷ and not all are children of Abraham because they are his descendants; but “Through Isaac shall your descendants be named.” ⁸ This means that it is not the children of the flesh who are the children of God, but the children of the promise are reckoned as descendants. ⁹ For this is what the promise said, “About this time I will return and Sarah shall have a son.”