Genesis 17:19-21

Young's Literal Translation

¹⁹ and God saith, `Sarah thy wife is certainly bearing a son to thee, and thou hast called his name Isaac, and I have established My covenant with him, for a covenant age-during, to his seed after him.

²⁰ As to Ishmael, I have heard thee; lo, I have blessed him, and made him fruitful, and multiplied him, very exceedingly; twelve princes doth he beget, and I have made him become a great nation;

²¹ and My covenant I establish with Isaac, whom Sarah doth bear to thee at this appointed time in the next year;'