Genesis 26:8-9

When he had been there a long time, Abimelech king of the Philistines looked out of a window and saw Isaac laughing with Rebekah his wife. So Abimelech called Isaac and said, “Behold, she is your wife. How then could you say, ‘She is my sister’?” Isaac said to him, “Because I thought, ‘Lest I die because of her.’”