Albert Barnes Commentary Ecclesiastes 10:3

"Yea also, when the fool walketh by the way, his understanding faileth him, and he saith to every one [that] he is a fool." — Ecclesiastes 10:3 (ASV)

“Way” may be understood either literally , or figuratively, as the course of action which he follows.

He saith ... — He exposes his folly to everyone he meets.