Carl Friedrich Keil and Franz Delitzsch Old Testament Commentary

The prophet announces this to them, and now tells openly what has been exhibited to him in his mental mirror as the purpose of God. "And nations become as lime burnings, thorns cut off, which are kindled with fire." The first simile sets forth the totality of the destruction: they will be so completely burned up, that nothing but ashes will be left, like the lump of lime left at the burning of lime. The second contains a figurative description of its suddenness: they have vanished suddenly, like dead brushwood, which is cut down in consequence, and quickly crackles up and is consumed (Isa 5:24, cf., Isa 9:17): kâsach is the Targum word for zâmar, amputare, whereas in Arabic it has the same meaning as sâchâh, verrere.