What is "li'Tzfunav"?
Rashi: For the sake of matters hidden for him.
Malbim: His hidden matters. He hides all his evil and theft in darkness, so no one sees it. Even though there is no light or fire there, Hashem will make a fire there, to consume all that he has, and light, to reveal his deeds under the sun.
Why is the fire not fanned?
Rashi: It is the fire of Gehinom.
Ibn Ezra: It is lest he die quickly.
Malbim: This is in order that it will consume all in his tent.
What is the meaning of "Yera Sarid b'Ahalo"?
Rashi: Evil will come to the remnant that will remain in his tent. The entire Parshah discusses Anshei Sedom. Even Lot, who was saved from them, evil came to his tent (wife) - she became a pillar of salt (Tanchuma Vayera 7).
Malbim: The fire will consume also what remains in his house, that he did not need to hide it.
