John Gill Commentary Ecclesiastes 10:15

"The labor of fools wearieth every one of them; for he knoweth not how to go to the city." — Ecclesiastes 10:15 (ASV)

The labour of the foolish wearies everyone of them. The labour of fools, both in speaking and doing, weary those who have any concern with them, and themselves likewise, since all their labour is vain and fruitless;

because he knows not how to go to the city. This refers to not knowing how to go to any city, the road to which is usually broad, plain, and easy to be found, and yet cannot be found by the foolish man. This shows that he who talks of abstruse things, things too high and wonderful for him, which he affects to know, must needs be a stranger to them, since he is ignorant of things the most easy to be understood, and yet wearies himself to find them; or it means he does not know how to behave himself in a city, among citizens, in a civil and polite manner.

The Targum is, "he learns not to go to the city, where wise men dwell, to learn instruction from it."

Some interpret it of the city of Jerusalem, where were the temple, sanhedrim, synagogues, schools, but it may be better applied to the heavenly city, the New Jerusalem, which fools or wicked men know not the way unto, nor do they seek after it; see (Psalms 107:7) (Matthew 7:13Matthew 7:14) ; so Alshech interprets it of heaven.