For thy mouth uttereth thine iniquity - Margin, "teacheth." That is, "your whole argument shows that you are a guilty man. A man who can defend such positions about God cannot be a pious man, or have any proper veneration for the Most High." A man may pursue an argument, and defend positions, that shall as certainly show that he is destitute of religion as though he lived an abandoned life; and he who holds opinions that are dishonorable to God, can no more be a pious man than if he dishonored God by violating his law.
Thou choosest the tongue of the crafty - Instead of pursuing an argument with candor and sincerity, you have resorted to miserable sophisms, such as running disputants use. You have not showed a disposition to ascertain and defend the truth, but have relied on the arts and evasions of the subtle disputant and the rhetorician. His whole discourse, according to Eliphaz, was a work of mere art, designed to blind his hearers; to deceive them with a favorable opinion of his piety; and to give some plausible, but delusive view of the government of God.

For thy mouth uttereth - In attempting to justify thyself, thou hast added iniquity to sin, and hast endeavored to impute blame to thy Maker.
The tongue of the crafty - Thou hast varnished thy own conduct, and used sophistical arguments to defend thyself. Thou resemblest those cunning persons, ערומים arumim, who derive their skill and dexterity from the old serpent, "the nachash, who was ערום arum, subtle, or crafty, beyond all the beasts of the field;" Genesis 3:1. Thy wisdom is not from above, but from beneath.

For thy mouth uttereth thine iniquity, and thou choosest the (d) tongue of the crafty.
(d) You speak as the mockers and contemners of God do.

For thy mouth uttereth thine iniquity,.... Which was in his heart, and so was an evidence against him, and proved him perverse, and made good the above charges exhibited against him: or "thine iniquity teaches thy mouth" (y); the wickedness that was in his heart prompted his mouth to speak the things he did, see Matthew 12:34; and this, as it was an instance of his folly, Proverbs 15:2; so a proof of his casting off the fear of the Lord; for if that had been before his eyes, he would have bridled his lips, and not uttered all the wickedness of his heart: for he that "bridleth not his tongue, this man's religion is vain", James 1:26;
and thou choosest the tongue of the crafty; coloured over things under specious pretences of religion and godliness, so that the simple and ignorant took him for a holy good man, when he was at heart an hypocrite; in this light Eliphaz puts Job, as one that walked and talked in craftiness, and was a deceitful worker, and imposed upon men with false glosses and plausible pretences.
(y) "docuit iniquitas tua os tuum", V. L. Pagninus, Bolducius; "docebit", Montanus; "docet", Piscator, Cocceius; so Tigurine version.

The sophistry of thine own speeches proves thy guilt.

כּי is not affirmative: forsooth (Hirz.), but, confirmatory and explicative. This opinion respecting him, which is so sharply and definitely expressed by אתּה, thrusts itself irresistibly forward, for it is not necessary to know his life more exactly, his own mouth, whence such words escape, reveals his sad state: docet (אלּף only in the book of Job, from אלף, discere, a word which only occurs once in the Hebrew, Proverbs 22:25) culpam tuam os tuum, not as Schlottm. explains, with Raschi: docet culpa tua os tuum, which, to avoid being misunderstood, must have been חטאתך תאלף, and is a though unsuited to the connection. אלּף is certainly not directly equivalent to הגּיד, Isaiah 3:9; it signifies to teach, to explain, and this verb is just the one in the mouth of the censorious friend. What follows must not be translated: while thou choosest (Hirz.); ותבחר is not a circumstantial clause, but adds a second confirmatory clause to the first: he chooses the language of the crafty, since he pretends to be able to prove his innocence before God; and convinced that he is in the right, assumes the offensive (as Job 13:4.) against those who exhort him to humble himself. Thus by his evil words he becomes his own judge (ירשׁיעך) and accuser (יענו בך after the fem. שׂפתיך, like Proverbs 5:2; Proverbs 26:23). The knot of the controversy becomes constantly more entangled since Job strengthens the friends more and more in their false view by his speeches, which certainly are sinful in some parts (as Job 9:22).

Uttereth - Thy words discover the naughtiness of thy heart. Crafty - Thou speakest wickedly, and craftily: thou coverest thy impious principles with fair pretences of piety.