Genesis 26:7-9

7And the men of the place asked about his wife. And he said, “She is my sister”; for he was afraid to say, “She is my wife,” because he thought, “lest the men of the place kill me for Rebekah, because she is beautiful to behold.”

8Now 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.

9Then 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.’ ”