Better, "Hatred is covered by deceit, but in the midst of the congregation his wickedness will be made manifest," i. e., then, in the time of need, the feigned friendship will pass into open enmity.

[Whose] hatred is covered by deceit, his wickedness shall be revealed before the [whole] (m) congregation.
(m) In the assembly of the godly.

Whose hatred is covered by deceit,.... The hatred of whose heart is covered by deceitful words, and strong expressions of love and esteem; so that those to whom they are made are deceived by them. Or, whose "hatred is covered in a waste or desert place" (n); it being not seen; as what is done in desert places is not obvious to view, being little frequented; which agrees with what follows, and keeps up the antithesis between the two clauses: Schultens renders it, with a tumultuous noise, with loud and public acclamations; see Zac 4:7;
his wickedness shall be showed before the whole congregation; in an open court of judicature, where he shall be brought, arraigned, and tried for his wickedness; which, though covertly done, shall be exposed and proved upon him: or before the church of God, where he shall be convicted by the word, and be obliged to acknowledge his sin; and, in a member, be reproved before all, and rejected: or however, at the great day of judgment, before angels and men, when all will be convened together; and where every secret work will be brought, and will be brought to light, and receive its just reward.
(n) "in desolatione", Montanus; "in solitudine", Baynus, Vatablus; "in vastatione", Tigurine version; "in vastitate", Mercerus, Piscator, so Ben Melech.

Deceit will at last be exposed, and the wicked by their own arts often bring on retribution (compare Proverbs 12:13; Psalm 7:16; Psalm 9:17, &c.).

26 Hatred may conceal itself behind deceit:
Its wickedness shall be exposed in the assembly.
Proverbs which begin with the fut. are rarely to be found, it is true; yet, as we have seen, Proverbs 12:26, they are sometimes to be met with in the collection. This is one of the few that are of such a character; for that the lxx and others translate ὁ κρύπτων, which gives for רעתו a more appropriate reference, does not require us to agree with Hitzig in reading הכּסה (Proverbs 12:16, Proverbs 12:23) - the two clauses rendered fut. stand in the same syntactical relation, as e.g., Job 20:24. Still less can the rendering of במשׁאון by συνίστησι δόλον, by the lxx, induce us to read with Hitzig חרשׁ און, especially since it is doubtful whether the Hebrews. words which floated before those translators (the lxx) have been fallen upon. משּׁאון (beginning and ending with a formative syllable) is certainly a word of rare formation, to be compared only to מסדּרון, Judges 3:23; but since the nearest-lying formation משּׁא signifies usury (from נשׁא, to credit) (according to which Symmachus, διὰ λήμματα, to desire gain), it is obvious that the language preferred this double formation for the meaning deceiving, illusion, or, exactly: fraud. It may also be possible to refer it, like משּׁוּאות (vid., under Psalm 23:1-6 :18), to שׁוא = שׁאה, to be confused, waste, as this is done by Parchon, Kimchi (Venet. ἐν ἐρημίᾳ), Ralbag, and others; משׁאון, in this sense of deepest concealment, certainly says not a little as the contrast of קהל [an assembly], but ישׁימום [a desert] stood ready for the poet to be used in this sense; he might also have expressed himself as Job 30:3; Job 38:27. The selection of this rare word is better explained if it denotes the superlative of deceit - a course of conduct maliciously directed toward the deception of a neighbour. That is also the impression which the word has made on Jerome (fraudulenter), the Targ. (בּמוּרסתא, in grinding), Luther (to do injury), and according to which it has already been explained, e.g., by C. B. Michaelis and Oetinger ("with dissembled, deceitful nature"). The punctuation of תכסה, Codd. and editions present in three different forms. Buxtorf in his Concordance (also Frst), and the Basel Biblia Rabbinica, have the form תּכסּה; but this is a mistake. Either תּכּסה (Niph.) תּכּסּה (Hithpa., with the same assimilation of the preformative ת as in הכּבּס, Leviticus 13:55; נכּפּר, Deuteronomy 21:8) is to be read; Kimchi, in his Wrterbuch, gives תּכּסּה, which is certainly better supported. A surer contrast of במשׁאון and בקהל remains in our interpretation; only we translate not as Ewald: "hatred seeks to conceal itself by hypocrisy," but: in deceitful work. Also we refer רעתו, not to במשׁאון, but to שׂנאה, for hatred is thought of in connection with its personal representative. We see from 26b that hatred is meant which not only broods over evil, but also carries it into execution. Such hatred may conceal itself in cunningly-contrived deception, yet the wickedness of the hater in the end comes out from behind the mask with the light of publicity.

Deceit - With false professions of love.