John Gills Exposition of the Bible Commentary - Proverbs 26:18
As a mad man , who casteth firebrands, arrows, and death. Or the instruments of death, as Aben Ezra; or the sharp arrows of death, as the Targum and Syriac version; who casts firebrands into the houses and barns of his neighbours, to consume them; or arrows at their persons and cattle, to destroy them; or any other instruments of death, which none but a mad man, or one wickedly mad, would do. Or, "as one that makes himself mad" F5 כמתלהלה "ut se habet qui iunsanum ne simulat",... read more
Matthew Henry's Complete Commentary - Proverbs 26:18-19
See here, 1. How mischievous those are that make no scruple of deceiving their neighbours; they are as madmen that cast firebrands, arrows, and death, so much hurt may they do by their deceits. They value themselves upon it as polite cunning men, but really they are as madmen. There is not a greater madness in the world than a wilful sin. It is not only the passionate furious man, but the malicious deceitful man, that is a madman; he does in effect cast fire-brands, arrows, and death; he does... read more