Why does it say "Laylah v'Yomam"?
Radak: Since it said that their land will be burning pitch (9), it says that their smoke will always rise, like Sedom and Amorah; smoke constantly rises from them.
Malbim: A fire for cooking, people extinguish it at night. A fire for illumination, people extinguish it during the day. This fire will not be extinguished day or night. It is in order that smoke will constantly rise.
What is "mi'Dor la'Dor"?
Rashi #1: From that generation until the last generation.
Rashi #2: This is Moshe's curse - "Milchamah la'Shem ba'Amalek mi'Dor Dor" (Shemos 17:16) - from Moshe's generation until Sha'ul's generation, and from then until Mordechai's generation, and from then until Melech ha'Mashi'ach.
Why does it say "Ein Over Bah"?
Malbim: Not only will it not be rebuilt. No one will even pass by haphazardly. Who would consider rebuilding it?!
