Ecclesiastes 8:6

Solomon had said (Ecc 8:5) that a wise man's heart discerns time and judgment, that is, a man's wisdom will go a great way, by the blessing of God, in moral prognostications; but here he shows that few have that wisdom, and that even the wisest may yet be surprised by a calamity which they had not any foresight of, and therefore it is our wisdom to expect and prepare for sudden changes. Observe, 1. All the events concerning us, with the exact time of them, are determined and appointed in the counsel and foreknowledge of God, and all in wisdom: To every purpose there is a time prefixed, and it is the best time, for it is time and judgment, time appointed both in wisdom and righteousness; the appointment is not chargeable with folly or iniquity. 2. We are very much in the dark concerning future events and the time and season of them: Man knows not that which shall be himself; and who can tell him when or how it shall be? Ecc 8:7. It cannot either be foreseen by him or foretold him; the stars cannot foretel a man what shall be, nor any of the arts of divination. God has, in wisdom, concealed from us the knowledge of future events, that we may be always ready for changes. 3.

— Matthew Henry's Concise Commentary (public domain)

therefore the misery, &c.--because the foolish sinner does not think of the right "times" and the "judgment."

— Jamieson-Fausset-Brown Commentary (public domain)