Seven abominations - Compare Proverbs 26:16 note. Here "seven" retains, perhaps, its significance as the symbol of completeness. Evil has, as it were, gone through all its work, and holds its accursed Sabbath in the heart in which all things are "very evil."

When he speaketh fair - For there are such hypocrites and false friends in the world.
Believe him not - Let all his professions go for nothing.
For there are seven abominations in his heart - That is, he is full of abominations.

When he speaketh kindly, believe him not: for [there are] (l) seven abominations in his heart.
(l) Meaning many: he uses a certain number for the uncertain.

When he speaketh fair, believe him not,.... Gives good words, flatters with his lips, pretends great kindness and favour, expresses himself in a very gracious and amiable manner, in order to gain attention and respect; or when he delivers himself in a submissive and suppliant way, with great humility and deference; or in a mournful and pitiful strain, as if he had the most tender affection and concern; be not too credulous; do not suffer yourselves to be imposed upon by him; be upon your guard, distrust him, suspect a snake in the grass;
for there are seven abominations in his heart; a multitude of wicked purposes, schemes, and designs, which he has formed there against you, and which he only waits a proper time to put in execution; things abominable to God and men. Aben Ezra thinks reference is had to the seven abominations in Proverbs 6:16.

Sentiment of Proverbs 26:24 carried out.
seven abominations in his heart--that is, very many (compare Proverbs 24:16).