Kabbalah zu Mischlej 28:1

Come and behold, the Shechinah did not leave Sarah at all during that night. When Pharaoh approached her, an angel came and hit him. And whenever Sarah said, "Hit," he hit. All the while Abraham was begging his Master through his prayers, not to allow anyone to harm her. Therefore, it is written, "But the righteous are bold (trusting) as a lion" (Proverbs 28:1). Here was a trial by which Hashem tested Abraham, but Abraham had no doubts about the Holy One, blessed be He.