Genesis 17:17

17:17 Then Abraham bowed down with his face to the ground and laughed as he said to himself, “Can a son be born to a man who is a hundred years old? Can Sarah bear a child at the age of ninety?”

Genesis 17:19

17:19 God said, “No, Sarah your wife is going to bear you a son, and you will name him Isaac. I will confirm my covenant with him as a perpetual covenant for his descendants after him.

Genesis 17:21

17:21 But I will establish my covenant with Isaac, whom Sarah will bear to you at this set time next year.”