John Gill Commentary Proverbs 26:25

"When he speaketh fair, believe him not; For there are seven abominations in his heart:" — Proverbs 26:25 (ASV)

When he speaks 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) .