Charles Ellicott 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)

That he is a fool. —In Hebrew, as in English, the antecedent of “he” may be taken differently, and so the Vulgate and other authorities understand the verse as meaning that the fool in his self-conceit attributes folly to everyone else. But it is better, as well as more obvious, to understand the verse as describing the self-betrayal of the fool (Proverbs 13:16; Proverbs 17:28; Proverbs 18:2).