Why does it say that their evil burns like fire?
Rashi: Their evil will burn them, and consume them like fire.
What does it say about Shamir v'Shayis?
Rashi: They will consume the rebels and intentional sinners among them.
Radak, Malbim: Normally, a fire begins to consume thorns and thin branches - "u'Matz'ah Kotzim" (Shemos 22:5). Afterwards, it burns big branches. So their evil will consume them. It will begin with the Ketanim (thorns), and afterwards "Sichvei ha'Ya'ar" (the branches). Malbim - however, the trunks themselves will not burn, just they will blacken due to the smoke, and not grow further. Also refer to 9:18:1:4.
What are "Sichvei ha'Ya'ar"?
Rashi: They are branches; they represent the lowly of the nation. Also refer to 9:17:2:2. Malbim - they represent the middle people. The great Resha'im (thorns) will burn first, and afterwards the Beinonim.
What is the meaning of "va'Yis'abchu Ge'us Ashan"?
Rashi: They will be confused and closed in the strength of the smoke and fire. "Va'Yis'abchu" is an expression of Navach (confusion). The root is only Beis and Chaf, like "mi'Bechi Neharos" (Iyov 28:11), "Emek ha'Bacha" (Tehilim 84:7). Sometimes the Nun is added. Here there is an Aleph in place of a Nun, like the Aleph in "Ivchas Cherev" (Yechezkel 21:20) and in "v'Achavasi b'Azneichem" (Iyov 13:17).
Radak: Based on context, "va'Yis'abchu" means 'they became haughty.' It is as if it says k'Ge'us Ashan; the prefix Kaf is omitted. Similarly, "Lev Somayach Yeitiv Gehah" (Mishlei 17:22) is like k'Gehah. Because it compared their evil to a burning fire, it says Tig'u - their smoke will rise like the rising of smoke. I.e. their evil deeds will be publicized until all nations know. Some see the smoke, but do not see the flame. So [even] the nations far from them will know their evil.
