When Avraham was coming to Mitzrayim with Sarah, he told her: "Imri Na Achosi At, Lima'an Yitav Li Ba'avureich, Ve'chaysah Nafshi Biglaleich" - "Say, please, that you are my sister, so they should do good for me, for you, and give me life because of you".
The Ba'al Shem T...