Midrasch zu Bereschit 19:17

A certain young man of the people of that city saw them, and he ran and told all the men of that city, and they all gathered together at the door of the house to do according to their wont, even deeds of sodomy, as it is said, "And they called unto Lot, and said unto him, || Where are the men who came to thee to-night? bring them forth unto us that we may know them" (Gen. 19:5). What did Lot do? Just as Moses gave his life for the people, so Lot gave up his two daughters instead of the two angels, as it is said, "Behold, now, I have two daughters" (Gen. 19:8). But the men would not agree (and did not accept them). What did the angels do to them? They smote them with blindness until the dawn of the (next) morning. All were treated with (measure for) measure. Just as he had taken them by the hand without their will and taken them into his house, so they took hold of his hand, and the hand of his wife, and the hand of his two daughters, and took them outside the city, as it is said, "But he lingered; and the men laid hold upon his hand" (Gen. 19:16). And they said to them: Do not look behind you, for verily the Shekhinah of the Holy One, blessed be He, has descended in order to rain upon Sodom and upon Gomorrah brimstone and fire. The pity of 'Edith the wife of Lot was stirred for her daughters, who were married in Sodom, and she looked back behind her to see if they were coming after her or not. And she saw behind the Shekhinah, and she became a pillar of salt, as it is said, "And his wife looked back from behind him, and she became a pillar of salt" (Gen. 19:26).