Genesis 26:8-10

And it came to pass, when he had been there a long time that Abimelech, king of the Philistines, looking out a window, saw Isaac sporting with Rebekah, his wife. And Abimelech called Isaac and said, Behold, of a surety she is thy wife; and how didst thou say, She is my sister? And Isaac said unto him, Because I said, Lest I die because of her. And Abimelech said, What is this thou hast done unto us? One of the people might easily have slept with thy wife, and thou should have brought the sin upon us.