Thematic Bible: Her miraculous conception of isaac

And God said unto Abraham, As for Sarai your wife, you shall not call her name Sarai, but Sarah shall her name be. And I will bless her, and give you a son also of her: yea, I will bless her, and she shall be a mother of nations; kings of people shall come from her. Then Abraham fell upon his face, and laughed, and said in his heart, Shall a child be born unto him that is a hundred years old? and shall Sarah, that is ninety years old, bear? read more.
And Abraham said unto God, O that Ishmael might live before you! And God said, Sarah your wife shall bear you a son indeed; and you shall call his name Isaac: and I will establish my covenant with him for an everlasting covenant, and with his descendants after him. And as for Ishmael, I have heard you: Behold, I have blessed him, and will make him fruitful, and will multiply him exceedingly; twelve princes shall he beget, and I will make him a great nation. But my covenant will I establish with Isaac, whom Sarah shall bear unto you at this set time in the next year.

And they said unto him, Where is Sarah your wife? And he said, Behold, in the tent. And he said, I will certainly return unto you according to the time of life; and, lo, Sarah your wife shall have a son. And Sarah heard it in the tent door, which was behind him. Now Abraham and Sarah were old and well stricken in age; and it ceased to be with Sarah after the manner of women. read more.
Therefore Sarah laughed within herself, saying, After I have grown old shall I have pleasure, my lord being old also? And the LORD said unto Abraham, Why did Sarah laugh, saying, Shall I of a certainty bear a child, who am old? Is anything too hard for the LORD? At the time appointed I will return unto you, according to the time of life, and Sarah shall have a son. Then Sarah denied, saying, I laughed not; for she was afraid. And he said, Nay; but you did laugh.