Genesis 18:12 (KJV)

And Abraham ran unto the herd, and fetcht a calf tender and good, and gave it unto a young man; and he hasted to dress it.

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.

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

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.

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

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

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.

Then Sarah denied, saying, I laughed not; for she was afraid. And he said, Nay; but thou didst laugh.

And the men rose up from thence, and looked toward Sodom: and Abraham went with them to bring them on the way.

And the LORD said, Shall I hide from Abraham that thing which I do;