He that hateth dissembleth with his lips,.... He that bears a grudge in his mind, and retains hatred in his heart against any person, hides it all he can, till he has an opportunity of showing it as he would; he pretends a great deal of friendship with his lips, that his hatred might not be known; he would be thought to be a friend, when he is really an enemy; he does not choose as yet to make himself known what he is. Some render it to a sense the reverse, "the enemy", or "he that hateth, is known by his lips" (l); so the Targum, Vulgate Latin, and Syriac versions: if you carefully watch him, mark his words, and observe what he says, you will find out the hatred that lies in his heart; he cannot forbear saying something, at one time or another, which betrays the malignity of his mind;
and layeth up deceit within him; or, "though (m) he layeth up", &c. hides it as much as he can, yet it will show itself in some way or another.
(l) "agnoscetur", Montanus, Vatablus; "cognoscetur", Tigurine version; "cognoscitur", Amama, so Luther. (m) "quamvis", Luther. apud Gejerus, Baynus.

Always distrust when a man speaks fair unless you know him well. Satan, in his temptations, speaks fair, as he did to Eve; but it is madness to give credit to him.

dissembleth--though an unusual sense of the word (compare Margin), is allowable, and better suits the context, which sets forth hypocrisy.

Proverbs 26:24 and Proverbs 26:25 form a tetrastich.
24 With his lips the hater dissembleth,
And in his heart he museth deceit.
25 If he maketh his voice agreeable, believe him not,
For seven abominations are in his heart.
All the old translators (also the Venet. and Luther) give to יגּכר the meaning, to become known; but the Niph. as well as the Hithpa. (vid., at Proverbs 20:11; Genesis 47:17) unites with this meaning also the meaning to make oneself known: to make oneself unknown, unrecognisable = (Arab.) tanakkr, e.g., by means of clothing, or by a changed expression of countenance.
(Note: Vid., de Goeje's Fragmenta Hist. Arab. ii. (1871), p. 94. The verb נכר, primarily to fix one's attention, sharply to contemplate anything, whence is derived the meanings of knowing and of not knowing, disowning. The account of the origin of these contrasted meanings, in Gesenius-Dietrich's Lexicon, is essentially correct; but the Arab. nakar there referred to means, not sharpness of mind, from nakar = הכּיר, but from the negative signification prevailing in the Arab. alone, a property by which one makes himself worthy of being disowned: craftiness, cunning, and then also in bonam partem: sagacity.)
The contrast demands here this latter signification: labiis suis alium se simulat osor, intus in pectore autem reconditum habet dolum (Fleischer). This rendering of ישׁית מרמה is more correct than Hitzig's ("in his breast) he prepares treachery;" for שׁית מרמה is to be rendered after שׁית עצות, Psalm 13:3 (vid., Hupfeld's and also our comm. on this passage), not after Jeremiah 9:7; for one says שׁית מוקשׁים, to place snares, שׁית ארב, to lay an ambush, and the like, but not to place or to lay deceit. If such a dissembler makes his voice agreeable (Piel of חנן only here, for the form Psalm 9:14 is, as it is punctuated, Kal), trust not thyself to him (האמין, with ב: to put firm trust in anything, vid., Genesis, p. 312)
(Note: The fundamental idea of firmness in האמין is always in the subject, not the object. The Arabic interpreters remark that âman with ב expresses recognition, and with ל submission (vid., Lane's Lexicon under âman); but in Hebr. האמין with ב fiducia fidei, with ל assensus fidei; the relation is thus not altogether the same.)
for seven abominations, i.e., a whole host of abominable thoughts and designs, are in his heart; he is, if one may express it, after Matthew 12:45, possessed inwardly of seven devils. The lxx makes a history of 24a: an enemy who, under complaints, makes all possible allowances, but in his heart τεκταίνεται δόλους. The history is only too true, but it has no place in the text.