| Barnes' Notes on the Bible The Hebrew counterpart to the Greek "Know thyself." "The highest wisdom is for a person to understand his own way. The most extreme folly is self-deceit." The word "deceit" may, however, involve fraud practiced upon others. The folly of fools shows itself then in their ceaseless effort to deceive.
Clarke's Commentary on the BibleIs to understand his way - Instead of הבין habin, to understand, הכין hachin, to Direct his way, is found in one MS. It makes a very good sense.
Gill's Exposition of the Entire BibleThe wisdom of the prudent is to understand his way,.... The way of his calling, in which he should abide, and how to manage it in the best manner; the way of his duty, that he may walk inoffensively both towards God and men; and the way of life and salvation, which is by Jesus Christ, which to understand and to walk in is the highest wisdom and prudence; but the folly of fools is deceit: or "the wisdom of fools", which the opposition requires, and is meant, and is what the Holy Ghost calls "folly", as elsewhere, 1 Corinthians 3:19; this is itself "deceit"; it is science, falsely so called; it lies in tricking and deceiving; and the issue of it is, not only the deceiving of others, but themselves also: such is the folly of the man of sin and followers, which lies in deceiving the inhabitants of the earth with their sorceries and superstitions, with their lying wonders and miracles; see 2 Thessalonians 2:10, Revelation 13:14.
Keil and Delitzsch Biblical Commentary on the Old Testament8 The wisdom of the prudent is to observe his way, And the folly of fools is deceit. The nearest idea is that of self-deceit, according to which the lxx, Syr., and Jerome render the word error ("Irrsal"). But מרמה is nowhere else used of self-deception, and moreover is not the suitable word for such an idea, since the conception of the dolus malus is constantly associated with it. Thus the contrast will be this: the wisdom of the prudent shows itself in this, that he considers his conduct (הבין as Proverbs 7:7, cf. Psalm 5:2), i.e., regulates it carefully, examining and considering (Proverbs 13:16) it according to right and duty; and that on the contrary the folly of fools shows itself in this, that they aim at the malevolent deception of their neighbour, and try all kinds of secret ways for the gaining of this end. The former is wisdom, because from the good only good comes; the latter is folly or madness, because deception, however long it may sneak in darkness, yet at last comes to light, and recoils in its destructive effects upon him from whom it proceeds.
Geneva Study BibleThe wisdom of the prudent is to understand his way: but the folly of fools is deceit.
Wesley's Notes 14:8 His way - Consists not in vain speculations, but in a diligent study of his duty, and of the way to eternal happiness. The folly - The wit of ungodly men, which is really their folly, is employed only in finding out ways of deceiving.
Jamieson-Fausset-Brown Bible Commentary8. Appearances deceive the thoughtless, but the prudent discriminate.
Matthew Henry's Concise Commentary14:1 A woman who has no fear of God, who is wilful and wasteful, and indulges her ease, will as certainly ruin her family, as if she plucked her house down. 2. Here are grace and sin in their true colours. Those that despise God's precepts and promises, despise God and all his power and mercy. 3. Pride grows from that root of bitterness which is in the heart. The root must be plucked up, or we cannot conquer this branch. The prudent words of wise men get them out of difficulties. 4. There can be no advantage without something which, though of little moment, will affright the indolent. 5. A conscientious witness will not dare to represent anything otherwise than according to his knowledge. 6. A scorner treats Divine things with contempt. He that feels his ignorance and unworthiness will search the Scriptures in a humble spirit. 7. We discover a wicked man if there is no savour of piety in his discourse. 8. We are travellers, whose concern is, not to spy out wonders, but to get to their journey's end; to understand the rules we are to walk by, also the ends we are to walk toward. The bad man cheats himself, and goes on in his mistake. 9. Foolish and profane men consider sin a mere trifle, to be made light of rather than mourned over. Fools mock at the sin-offering; but those that make light of sin, make light of Christ. 10. We do not know what stings of conscience, or consuming passions, torment the prosperous sinner. Nor does the world know the peace of mind a serious Christian enjoys, even in poverty and sickness. 11. Sin ruins many great families; whilst righteousness often raises and strengthens even mean families. 12. The ways of carelessness, of worldliness, and of sensuality, seem right to those that walk in them; but self-deceivers prove self-destroyers. See the vanity of carnal mirth. 14. Of all sinners backsliders will have the most terror when they reflect on their own ways. 15. Eager readiness to believe what others say, has ever proved mischievous. The whole world was thus ruined at first. The man who is spiritually wise, depends on the Saviour alone for acceptance. He is watchful against the enemies of his salvation, by taking heed to God's word. 16. Holy fear guards against every thing unholy. 17. An angry man is to be pitied as well as blamed; but the revengeful is more hateful.
Matthew Henry's Whole Bible CommentaryVerse 8 See here, 1. The good conduct of a wise and good man; he manages himself well. it is not the wisdom of the learned, which consists only in speculation, that is here recommended, but the wisdom of the prudent, which is practical, and is of use to direct our counsels and actions. Christian prudence consists in a right understanding of our way; for we are travellers, whose concern it is, not to spy wonders, but to get forward towards their journey's end. It is to understand our own way, not to be critics and busybodies in other men's matters, but to look well to ourselves and ponder the path of our feet, to understand the directions of our way, that we may observe them, the dangers of our way, that we may avoid them, the difficulties of our way, that we may break through them, and the advantages of our way, that we may improve them-to understand the rules we are to walk by and the ends we are to walk towards, and walk accordingly. 2. The bad conduct of a bad man; he puts a cheat upon himself. He does not rightly understand his way; he thinks he does, and so misses his way, and goes on in his mistake: The folly of fools is deceit; it cheats them into their own ruin. The folly of him that built on the sand was deceit. | 
