Verse 8: But the tongue can no man tame; it is an unruly evil, (Ps. 140:3) full of deadly poison.
[But the tongue can no man tame] Tongue understand as, either, 1. one’s own (certain interpreters in Estius, Gataker): no one, that is, few (Cameron), almost no one. It is Hyperbole, of which sort is found in Isaiah 64:7; Micah 7:2 (Gataker). Or, no one, in such a way that he does not sometimes slip (Gataker, other interpreters in Estius); or, no one of himself and in his own strength, without the grace of God (Estius and Gataker out of Augustine). Or rather, 2. another’s (Estius, Grotius); which inflicts a wound, both inevitable and incurable: that is to say, There is not one that could restrain another’s tongue from detractions, indignities, quarreling, lies, etc. (Estius).
But the tongue; not only other men’s tongues, but his own. Can no man tame; no man of himself, and without the assistance of Divine grace, can bring his tongue into subjection, and keep it in order; nor can any man, by the assistance of any grace promised in this life, so keep it, as that it shall never at all offend.
[A restless, etc., ἀκατάσχετον κακόν] Supply ἐστὶ, it is, which the following member shows (Grotius). It is an evil irrepressible (Erasmus, Illyricus, Tigurinus, Vatablus), or, unruly (Castalio), which is not able to be restrained (Grotius), which thou art not able restrain (Pagnine, Beza, Piscator, similarly Tremellius, Arabic), without it bursting through broken bars, and proceeding unto the hurt of men, although nature has opposed to it the twofold fence of the lips and of the teeth (Estius).
It is an unruly evil; or, which cannot be restrained, and kept within bounds: wild beasts are kept in by grates and bars, but this by no restraint.
[Full of deadly venom (thus Pagnine, Beza, Piscator, etc.)] The language of θανατηφόρου/death-bearing is found in the writings of the Greek Poets, and in the Greek of Numbers 18:22 and Job 33:23; θανάσιμον/deadly, in Mark 16:18, is the same. In the same sense we have the cruel venom of asps, Deuteronomy 32:33. A false charge is like a poisoned dart, said Cicero (Grotius). Formerly venenum/poison/drug was a neutral word; today it is taken for the worse (Drusius). The sense: It is also ready to inflict most grievous and lethal injuries on others (Estius): The reputation of the neighbor, one’s own, and of the hearer, the very soul, and often also the bodies of many, it kills through the hatreds, quarrels, and wars that it kindles (Menochius).
Full of deadly poison; the wickedness of the tongue is compared to poison, in respect of the mischief it doth to others. It seems to allude to those kinds of serpents which have poison under their tongues, Psalm 140:3, with which they kill those they bite. The poison of the tongue is no less deadly, it murders men’s reputations by the slanders it utters, their souls by the lusts and passions it stirs up in them, and many times their bodies too by the contentions and quarrels it raiseth against men.
 Greek: τὴν δὲ γλῶσσαν οὐδεὶς δύναται ἀνθρώπων δαμάσαι· ἀκατάσχετον κακόν, μεστὴ ἰοῦ θανατηφόρου.
 For example, Æschylus’ Libation Bearers 369; Sophocles’ Œdipus Tyrannus 181.
 Numbers 18:22: “Neither must the children of Israel henceforth come nigh the tabernacle of the congregation, lest they bear sin, and die (לָשֵׂ֥את חֵ֖טְא לָמֽוּת׃; λαβεῖν ἁμαρτίαν θανατηφόρον, to bear a deadly sin, in the Septuagint).”
 Job 33:23: “If there be a messenger (מַלְאָךְ; χίλιοι ἄγγελοι θανατηφόροι, a thousand death-bearing angels, in the Septuagint) with him, an interpreter, one among a thousand, to shew unto man his uprightness…”
 Pro Publio Quinctio 2.