Genesis 20:10-13

10And Abimelek asked Abraham, “What was your reason for doing this?” 11Abraham replied, “I said to myself, ‘There is surely no fear of God in this place, and they will kill me because of my wife.’ 12Besides, she really is my sister, the daughter of my father though not of my mother; and she became my wife.

13And when God had me wander from my father’s household, I said to her, ‘This is how you can show your love to me: Everywhere we go, say of me, “He is my brother.” ’ ”