The gin - Another method of taking wild beasts. It was a snare so made as to spring suddenly on an animal, securing him by the neck or feet. We use a trap for the same purpose. The Hebrew word (פח pach) may denote anything of this kind - a snare, net, noose, etc. with which birds or wild animals are taken.
By the heel - By the foot.
And the robber shall prevail - He shall be overpowered by the highwayman; or the plunderer shall make a sudden descent upon him, and strip him of his all. The meaning is, that destruction would suddenly overtake him. There can be no doubt that Bildad meant to apply all this to Job.

The gin shall take him - Houbigant reads the tenth before the ninth verse, thus: "The snare is laid for him in the ground, and a trap for him in the way. The gin shall take him by the heel, and the robber shall prevail against him." From the beginning of the seventh verse to the end of the thirteenth there is an allusion to the various arts and methods practiced in hunting. 1. A number of persons extend themselves in a forest, and drive the game before them, still straitening the space from a broad base to a narrow point in form of a triangle, so that the farther they go the less room have they on the right and left, the hunters lining each side, while the drovers with their dogs are coming up behind. "The steps of his strength shall be straitened," Job 18:7. 2. Nets, gins, and pitfalls, are laid or formed in different places, so that many are taken before they come to the point where the two lines close. "He is cast into a net, he walketh upon a snare - the trap is laid for him in the way - the snare in the ground," Job 18:8-10. 3. The howling of the dogs, with the shouts of the huntsmen, fill him with dismay, and cause him to run himself beyond his strength and out of breath. "Terrors shall make him afraid on every side, and shall drive him to his feet," Job 18:11. 4. While spent with hunger and fatigue, he is entangled in the spread nets; and the huntsman either pierces him with an arrow or spear, or cuts the sinews of his legs, so that he is easily captured and destroyed. "The robbers shall prevail against him," Job 18:9. "His strength is hunger-bitten, and destruction is ready at his side," Job 18:12. This latter verse is thus paraphrased by the Chaldee: "Let his first-born son be famished; and affliction be prepared for his wife."

The gin shall take him by the heel,.... And hold him fast, so that he shall not be able to get away, especially out of such as are set by God himself; for God has his nets, and snares, and gins for wicked men, and such plenty of them, that he even is said to rain them on them; yea, he himself is a gin and a snare unto them, and out of his hands there is no escaping, wherefore it is a terrible thing to fall into them, see Ezekiel 12:13;
and the robber shall prevail against him; either robbers literally taken, such as the Sabeans and Chaldeans, to whom Bildad may have reference, who prevailed against Job, and plundered him of his substance; and such as these, as the word signifies, are "thirsty ones" (p), who thirst after the wealth and riches of men, and after their blood for the sake thereof, bloodthirsty ones; Mr. Broughton renders it, "the savage", barbarous, wild, and uncivilized, that lived in desert places, and were like wild beasts, let their hair grow long, to make them look more terrible and formidable, which some take to be the signification of the word, and render it "horrid" (q) or terrible; see Gill on Job 5:5; or else the devil may be meant, who is like a roaring lion, terrible and frightful, and who, as he was a murderer from the beginning, so a thief and robber, that comes to kill and destroy, and whom God suffers to prevail over the children of disobedience, and in whom he works powerfully, being the strong man armed, that has possession of them and their goods, and keeps them in peace; and who has his snares, which he lays suited to the tempers and dispositions of men, and in which they are taken alive, as beasts of prey, and are detained by him at his pleasure, 2-Timothy 2:26.
(p) "sitibundos", Montanus; "sitibundus", Tigurine version. (q) "Horridus", Junius & Tremellius, Cocceius, Schmidt.

robber--rather answering to "gin" in the parallel clause, "the noose shall hold him fast" [UMBREIT].