Genesis 18:11

He took butter, milk, and the calf which he had dressed, and set it before them. He stood by them under the tree, and they ate.

They asked him, “Where is Sarah, your wife?”

He said, “There, in the tent.”

He said, “I will certainly return to you at about this time next year; and behold, Sarah your wife will have a son.”

Sarah heard in the tent door, which was behind him.

Sarah laughed within herself, saying, “After I have grown old will I have pleasure, my lord being old also?”

The LORD said to Abraham, “Why did Sarah laugh, saying, ‘Will I really bear a child when I am old?’

Is anything too hard for the LORD? At the set time I will return to you, when the season comes around, and Sarah will have a son.”