"She is my sister"
Before Abraham goes down into the land of Egypt, he attaches himself to the divine presence known as the Shechinah. The word Egypt is a code for negativity and darkness. The spiritual principle concealed in this story can be revealed by an analogy. If a person lowers himself into a deep, darkened pit, filled with deadly snakes, to retrieve a great treasure, he first secures himself to a powerful rope to ensure a safe retreat. The rope becomes his lifeline as he enters into a dangerous environment. Abraham attached himself to the force called Shechinah before he entered into the pit of negativity [Egypt] so that he would maintain a lifeline to the Creator.
There are moments in life when negative situations consume us. Without supernal assistance, we fall prey to the traps and lures set up by the forces of negativity. We are building for ourselves a secure lifeline to the Creator for those difficult moments in life when we stumble and fall into negativity.