Genesis 26:8-9

Now it came to pass, when he had been there a long time, that Abimelech king of the Philistines looked through a window, and saw, and there was Isaac, showing endearment to Rebekah his wife. Then Abimelech called Isaac and said, “Quite obviously she is your wife; so how could you say, ‘She is my sister’?” Isaac said to him, “Because I said, ‘Lest I die on account of her.’ ”