Kabbalah for Genesis 26:7

"And the men of the place asked him of his wife; and he said, 'She is my sister" (Gen. 26:7), that is, just like Abraham said. For the Shechinah was with Isaac and his wife, and he said of the Shechinah, as it is written, "Say to wisdom, 'you are my sister'" (Mishlei 7:4). Thus, he was strengthened and said, "She is my sister." Abraham and Isaac deserved (to say this). This is assuredly so because of the verse "My sister, my love, my dove, my undefiled" (Shir Hashirim 5:2). (They) were therefore worthy of saying "She is my sister." Thus, the Righteous were strengthened by the Holy One, blessed be He.