John Gill Commentary Proverbs 18:7

"A fool`s mouth is his destruction, And his lips are the snare of his soul." — Proverbs 18:7 (ASV)

A fool's mouth [is] his destruction
The cause of it; for his contentions, and quarrels, and evil speaking, lawsuits are commenced against him, which bring ruin upon himself and his family now; as well as for his idle and wicked words he will be condemned hereafter, (Matthew 12:35) ; there is a world of iniquity in the mouth and tongue of a wicked man, which bring destruction upon himself and others, (James 3:6James 3:8) ;

and his lips [are] the snare of his soul ;
from speaking in his own defence, he says things which should not be said, and by which he is entangled yet more and more; he is caught by his own words and condemned by them; or his loquacity, in which he delights, is a snare unto him to say things which neither become him, nor are for his advantage, but the contrary; see (Proverbs 12:13) .