"And it came to pass, when Abram was come into Egypt" (Genesis 12:14). So the verse tells us, matter-of-factly. But where was Sarah?
The midrash fills the silence. Abraham, knowing how a king's eye falls on a beautiful woman, had built a chest and locked her inside it, so that no stranger's gaze could rest on her. When he came to the border customs house, the officers demanded the chest be opened.
Abraham tried to pay his way out. "You are carrying garments," they said, and he offered the tariff for garments. "No, it is gold," they said, and he offered the tariff for gold. "No, it is costly silks, perhaps even pearls," and he offered the tariff for those too. Each time he raised the price rather than open the lid.
At last the officers would not be refused, and Abraham lifted the cover. When he did, the whole land of Egypt was illumined by her beauty, as if the sun had come up a second time inside a stone house.
The sages are telling us that righteousness has a light of its own, and that modesty does not hide light — it only waits to be revealed.
(From the 1901 Hebraic Literature anthology, drawing on Bereshit Rabbah 40.)