Genesis 18:11

8 And he took butter, and milk, and the calf which he had dressed, and set it before them; and he stood by them under the tree, and they did eat.

9 And they said unto him, Where is Sarah thy wife? And he said, Behold, in the tent.

10 And he said, I will certainly return unto thee according to the time of life; and, lo, Sarah thy wife shall have a son. And Sarah heard it in the tent door, which was behind him.

11 Now Abraham and Sarah were old and well stricken in age; and it ceased to be with Sarah after the manner of women.

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

13 And the LORD said unto Abraham, Wherefore did Sarah laugh, saying, Shall I of a surety bear a child, which am old?

14 Is any thing too hard for the LORD? At the time appointed I will return unto thee, according to the time of life, and Sarah shall have a son.