Albert Barnes Commentary Ecclesiastes 7:14

"In the day of prosperity be joyful, and in the day of adversity consider; yea, God hath made the one side by side with the other, to the end that man should not find out anything [that shall be] after him." — Ecclesiastes 7:14 (ASV)

Good and prosperous days are in God’s design special times for comfort and rejoicing; the days of affliction and trouble are in God’s design the proper seasons for recollection and serious consideration.

The Providence of God has so arranged it that our good and evil days are intermingled with each other. This mixture of good and evil days is so proportioned by Divine Providence that it sufficiently justifies God’s dealings toward the sons of men, and counters all their discontent and complaints against Him.

Set the one over against the other — Rather, God made this as well as that, that is, the day of adversity as well as the day of prosperity. The apparent imitation of this passage in Ecclesiasticus strongly suggests that this book was written before the days of the son of Sirach.

To the end ... — God has established the alternation of prosperity and adversity in such a way that man cannot foresee the events that will follow when he is removed from his present state. Compare to the note on Ecclesiastes 6:12.