Genesis 26:7-9

7Now the men of the place asked about his wife. So he said, “She is my sister,” because he was afraid to say, “my wife”—“or else the men of the place would kill me on account of Rebekah, because she’s good looking.”

8Now after he had been there for a long time, King Abimelech of the Philistines peered down through the window and saw, behold, Isaac caressing his wife Rebekah.

9So Abimelech called Isaac and said, “So in fact she’s your wife! Now how could you say, ‘She’s my sister’?” Isaac said to him, “Because I said, ‘Or else I might die because of her.’”