Genesis 26:8-10

And it happened that, when he had been there a long time, Abimelech the king of the Philistines looked through the window, and saw—behold—Isaac was fondling Rebekah his wife. And Abimelech called Isaac and said, “Surely she is your wife. Now why did you say ‘She is my sister’?” And Isaac said to him, “Because I thought I would die on account of her.” And Abimelech said, “What is this you have done to us? One of the people might easily have slept with your wife! Then you would have brought guilt upon us!”