Genesis 26:7-8, 10

When the men of that place asked him about his wife, he said, “She is my sister,” because he was afraid to say, “She is my wife.” He thought, “The men of this place might kill me on account of Rebekah, because she is beautiful.” When Isaac had been there a long time, Abimelek king of the Philistines looked down from a window and saw Isaac caressing his wife Rebekah.

Then Abimelek said, “What is this you have done to us? One of the men might well have slept with your wife, and you would have brought guilt upon us.”