Genesis 20:2, 5, 12-13

Abraham said of Sarah his wife, “She is my sister.” So Abimelech king of Gerar sent and took Sarah.

Did he not himself say to me, ‘She is my sister’? And she herself said, ‘He is my brother.’ In the integrity of my heart and the innocence of my hands I have done this.”

Besides, she actually is my sister, the daughter of my father, but not the daughter of my mother, and she became my wife; and it came about, when God caused me to wander from my father’s house, that I said to her, ‘This is the kindness which you will show to me: everywhere we go, say of me, “He is my brother.” ’ ”