Genesis 17:21 in the King James Version
But my covenant will I establish with Isaac, which Sarah shall bear unto thee at this set time in the next year.
Context
20 As for Ishmael, I have heard you. Behold, I have blessed him, and will make him fruitful, and will multiply him exceedingly. He will become the father of twelve princes, and I will make him a great nation.
21 But I will establish my covenant with Isaac, whom Sarah will bear to you at this set time next year.”
22 When he finished talking with him, God went up from Abraham.