Then Abraham fell upon his face, and laughed, and said in his heart, Shall [a child] be born unto him that is an hundred years old? and shall Sarah, that is ninety years old, bear? (17:17)

Therefore Sarah laughed within herself, saying, After I am waxed old shall I have pleasure, my lord being old also? (18:12)

For Sarah conceived, and bare Abraham a son in his old age, at the set time of which God had spoken to him. (21:2)