For he is cast into a net by his own feet - He is caught in his own tricks, as if he had spread a net or dug a pitfall for another, and had fallen into it himself. The meaning is, that he would bring ruin upon himself while he was plotting the rain of others; see Psalm 9:16, "The wicked is snared by the work of his own hands;" compare the note at Job 5:13. The phrase "by his own feet" here means, that he walks there himself. He is not led or driven by others, but he goes himself into the net. Wild animals are sometimes driven, but he walks along of his own accord into the net, and has no one to blame but himself.
And he walketh upon a snare - Or a pitfall. This was formerly the mode of taking wild beasts. It was done by excavating a place in the earth, and covering it over with turf, leaves, etc. supported in a slender manner; so that the lion, or elephant or tiger that should tread on it, would fall through. These methods of taking wild beasts have been practiced from the earliest times, and are practiced everywhere.

For he is cast into a net - His own conduct will infallibly bring him to ruin. He shall be like a wild beast taken in a net; the more he flounces in order to extricate himself, the more he shall be entangled.
He walketh upon a snare - He is continually walking on the meshes of a net, by which he must soon be entangled and overthrown.

For he is cast into a net by his own feet, and he (f) walketh upon a snare.
(f) Meaning, that the wicked are in continual danger.

For he is cast into a net by his own feet,.... He goes into it of himself, incautious and imprudent; the counsels, schemes, and methods he takes to hurt others, issue in his own ruin; the pit he digs for them, he falls and sinks into himself; and the net which he has spread and hid for others, in it is his own foot taken; and the ways and means he takes to do himself good, to amass riches and advance his family, being illicit ones, prove snares and nets unto him, those leading him into many foolish and hurtful lusts, which bring him to perdition, Psalm 9:15; even the various sins and transgressions he commits are snares unto him, by which he is enticed and drawn in: for in "the transgression of an evil man there is a snare", Proverbs 29:6; these promise him peace, and pleasure, and liberty, but give neither; they are nets in which he is entangled, and cords by which he is held, Psalm 9:15; into which his own feet carry him: some render it, "he goes with a net at his feet" (n), or with his feet in a net; he cannot go where he would, or do as he pleases; he is restrained by the providence of God; as the devils are held in chains, so the feet of wicked men are entangled in a net, that they cannot move and act as they are desirous of:
and he walketh upon a snare: laid for him, and hidden to him, and therefore walks on boldly and unconcerned, not being apprehensive of any danger, though greatly exposed to it; he walks on as on firm and good ground, and in a broad road, but destruction and misery are in his ways; yet he walks on of himself willingly, and with all his strength, pleasing himself in the path he treads, not dreaming of the mischief that awaits him; or "upon a thicket" (o) of thorns and briers, his sins and iniquities with which he is entangled, and out of which he cannot extricate himself, or afflictive providences with which his way is hedged up; though the former sense seems best; Mr. Broughton renders it, "a platted gin".
(n) "nam it cum reti in pedibus suis", Cocceius. (o) "in perplexo", Cocceius.

he walketh upon--rather, "he lets himself go into the net" [UMBREIT]. If the English Version be retained, then understand "snare" to be the pitfall, covered over with branches and earth, which when walked upon give way (Psalm 9:15; Job 35:8).

8 For he is driven into the net by his own feet,
And he walketh over a snare.
9 The trap holdeth his heel fast,
The noose bindeth him.
10 His snare lieth hidden in the earth,
His nets upon the path;
11 Terrors affright him on every side,
And scare him at every step.
The Pual שׁלּח signifies not merely to be betrayed into, but driven into, like the Piel, Job 30:12, to drive away, and as it is to be translated in the similar passage in the song of Deborah, Judges 5:15 : "And as Issachar, Barak was driven (i.e., with desire for fighting) behind him down into the valley (the place of meeting under Mount Tabor);" בּרגליו, which there signifies, according to Judges 4:10; Judges 8:5, "upon his feet = close behind him," is here intended of the intermediate cause: by his own feet he is hurried into the net, i.e., against his will, and yet with his own feet he runs into destruction. The same thing is said in Job 18:8; the way on which he complacently wanders up and down (which the Hithp. signifies here) is שׂבכה, lattice-work, here a snare (Arab. schabacah, a net, from שׂבך, schabaca, to intertwine, weave), and consequently will suddenly break in and bring him to ruin. This fact of delivering himself over to destruction is established in apocopated futt. (Job 18:9) used as praes., and without the voluntative signification in accordance with the poetic licence: a trap catches a heel (poetic brevity for: the trap catches his heel), a noose seizes upon him, עליו (but with the accompanying notion of overpowering him, which the translation "bind" is intended to express). Such is the meaning of צמּים here, which is not plur., but sing., from צמם (Arab. ḍmm), to tie, and it unites in itself the meanings of snare-layer (Job 5:5) and of snare; the form (as אבּיר, אדּיר) corresponds more to the former, but does not, however, exclude the latter, as תּנּין and לפּיד (λαμπάς) show.
The continuation in Job 18:10 of the figure of the fowler affirms that that issue of his life (Job 18:9) has been preparing long beforehand; the prosperity of the evil-doer from the beginning tends towards ruin. Instead of חבלו we have the pointing חבלו, as it would be in Arab. in a similar sense hhabluhu (from hhabl, a cord, a net). The nearer destruction is now to him, the stronger is the hold which his foreboding has over him, since, as Job 18:11 adds, terrible thoughts (בּלּהות) and terrible apparitions fill him with dismay, and haunt him, following upon his feet. לרגליו, close behind him, as Genesis 30:30; 1-Samuel 25:42; Isaiah 41:2; Habakkuk 3:5. The best authorized pointing of the verb is והפיצהוּ, with Segol (Ges. 104, 2, c), Chateph-Segol, and Kibbutz. Except in Habakkuk 3:14, where the prophet includes himself with his people, הפיץ, diffundere, dissipare (vid., Job 37:11; Job 40:11), never has a person as its obj. elsewhere. It would also probably not be used, but for the idea that the spectres of terror pursue him at every step, and are now here, now there, and his person is as it were multiplied.

Feet - By his own designs and actions.