Genesis 17:15-17

God also said to Abraham: “Concerning your wife Sarai, you are not to call her Sarai anymore, but Sarah, ‘My Princess,’ will be her name. I will wonderfully bless her, and I will certainly give you a son through her. Yes, I will bless her greatly, and she will become a mother of nations; kings of nations will arise among her children!” Then Abraham laughed so hard he fell to the ground, saying to himself, “How in the world can a hundred-year-old man become a father? How can my wife Sarah get pregnant at ninety?”