Genesis 26:8-11

When Isaac had been there for some time, Abimelech king of the Philistines looked down from the window and was surprised to see Isaac caressing his wife Rebekah. Abimelech sent for Isaac and said, “So she is really your wife! How could you say, ‘She is my sister’? ” Isaac answered him, “Because I thought I might die on account of her.” Then Abimelech said, “What is this you’ve done to us? One of the people could easily have slept with your wife, and you would have brought guilt on us.” So Abimelech warned all the people with these words: “Whoever harms this man or his wife will certainly die.”