For wrath killeth the foolish man - That is, the wrath of God. The word foolish here is used as synonymous with wicked, because wickedness is supreme folly. The general proposition here is, that the wicked are cut off, and that they are overtaken with heavy calamities in this life. In proof of this, Eliphaz appeals in the following verses to his own observation: The implied inference is, that Job, having had all his possessions taken away, and having been overwhelmed with unspeakably great personal calamities, was to be regarded as having been a great sinner. Some suppose, however, that the word "wrath" here relates to the indignation or the repining of the individual himself, and that the reference is to the fact that such wrath or repining preys upon the spirit, and draws down the divine vengeance. This is the view of Schultens, and of Noyes. But it seems more probable that Eliphaz means to state the proposition, that the wrath of God burns against the wicked, and that the following verses are an illustration of this sentiment, derived from his own observation.
And envy - Margin, "indignation." Jerome, invidia, envy. Septuagint ζῆλος zēlos. Castellio, severitas ac vehementia. The Hebrew word קנאה qı̂n'âh means jealousy, envy, ardor, zeal. It may be applied to any strong affection of the mind; any fervent, glowing, and burning emotion. Gesenius supposes it means here envy, as excited by the prosperity of others. To me it seems that the connection requires us to understand it of wrath, or indignation, as in Deuteronomy 29:20; Psalm 79:5. As applied to God, it often means his jealousy, or his anger, when the affections of people are placed on other objects than himself; Numbers 25:11; Zephaniah 1:18, et al.
Slayeth the silly one - Good and Noyes render this, "the weak man." Jerome, parvulum, the little one. The Septuagint, πεπλανημένον peplanēmenon, the erring. Walton, ardelionem, the busy-body. The Hebrew word פתה poteh is from פתה pâthâh, to open, go expand; and hence, the participleis applied to one who opens his lips, or whose mouth is open; that is, a garrulous person, Proverbs 20:19; and also to one who is open-hearted, frank, ingenuous, unsuspicious; and hence, one who is easily influenced by others, or whose heart may be easily enticed. Thus, it comes to mean one who is simple and foolish. In this sense it is used here, to denote one who is so simple and foolish as to be drawn aside by weak arguments and unfounded opinions. I have no doubt that Eliphaz meant, by insinuation, to apply this to Job, as being a weak-minded man, for having allowed the views which he entertained to make such an impression on his mind, and for having expressed himself as he had done. The proposition is general; but it would be easy to undertand how he intended it to be applied.

For wrath killeth the foolish man - Foolish, silly, and simple, are epithets given by Solomon to sinners and transgressors of all kinds. Such parallelisms have afforded a presumptive argument that Solomon was the author of this book. See the preface. The words of Eliphaz may be considered as a sort of maxim, which the wisdom and experience of ages had served to establish; viz., The wrath of God is manifested only against the wicked and impious; and if thou wert not such, God would not thus contend with thee.

For (b) wrath killeth the foolish man, and envy slayeth the silly one.
(b) Murmuring against God in afflictions increases the pain, and uttered man's folly.

For wrath killeth the foolish man,.... Not one that is an idiot, and destitute of common sense, and has no understanding in things natural and civil; but a wicked man, who has no knowledge of things divine and spiritual, and so foolish; which is the character of every natural man, and of God's people before conversion; and even of some professors, who are foolish virgins, and carry the lamp of a religious profession without the oil of grace; and such an one Eliphaz took Job to be, whom sooner or later the wrath of the Lord, as the Targum interprets it, which is revealed from heaven, and comes down upon the children of disobedience, would consume like devouring fire: or this may be understood of the wrath and passion of such men themselves, which sometimes rises in them to such an height, as that they die in a fit of it; or do those things which bring them to death, either by the hand of God, or by the civil magistrate:
and envy slayeth the silly one; one that is simple and void of understanding, and is easily persuaded and drawn into sin, either by his own heart, or by evil men, or by the temptations of Satan; and in whose heart envy at the prosperity of others dwells, and which insensibly preys upon him, eats up his own spirits, and is rottenness to his bones, and crumbles them into dust, Proverbs 14:30; or the word may be rendered "jealousy", or "zeal" (q), as it sometimes is, and may signify the jealousy of the Lord, zeal for his own glory, which he sometimes stirs up as a man of war, and which smokes against wicked men, and consumes them as fire, see Isaiah 42:13; Eliphaz by all this would represent and insinuate that Job was such a man, hot, passionate, and angry with God and his providence, and envious at the prosperity of others, particularly his friends; and so was a foolish and silly man, in whose breast wrath and envy rested, and would be his ruin and destruction, as he was already under slaying and killing providences.
(q) "zelus", Vatablus, Junius & Tremellius, Piscator, Schmidt, Michaelis, Schultens.

wrath . . . envy--fretful and passionate complaints, such as Eliphaz charged Job with (Job 4:5; so Proverbs 14:30). Not, the wrath of God killeth the foolish, and His envy, &c.

Killeth - A man's wrath, and impatience, preys upon his spirit, and so hastens his death; and provokes God to cut him off. The foolish - The rash and inconsiderate man, who does not weigh things impartially. Envy, &c. - I perceive thou art full of envy at wicked men, who seem to be in a happier condition than thou, and of wrath against God; and this shews thee to be a foolish and weak man. For those men, notwithstanding their present prosperity, are doomed to great and certain misery. I have myself seen the proof of this.