Genesis 12:19 Why saidst thou, She is my sister ? so I might have taken her to me to wife: now therefore behold thy wife, take her, and go thy way. (Abram said this to Pharaoh when he went down into Egypt. Sarai was Abram's half sister)
Genesis 20:2 And Abraham said of Sarah his wife, She is my sister : and Abimelech king of Gerar sent, and took Sarah.
Genesis 20:5 Said he not unto me, She is my sister ? and she, even she herself said, He is my brother: in the integrity of my heart and innocency of my hands have I done this.
Genesis 20:12 And yet indeed she is my sister ; she is the daughter of my father, but not the daughter of my mother; and she became my wife. (Sarah was Abraham's half sister)
Genesis 26:7 And the men of the place asked him of his wife; and he said, She is my sister : for he feared to say, She is my wife; lest, said he, the men of the place should kill me for Rebekah; because she was fair to look upon. (Rebekah was really Isaac's cousin)
Genesis 26:9 And Abimelech called Isaac, and said, Behold, of a surety she is thy wife: and how saidst thou, She is my sister ? And Isaac said unto him, Because I said, Lest I die for her.