Genesis 18:8-10 King James Version (KJV)
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.