Be afflicted, and mourn, and weep - That is, evidently, on account of your sins. The sins to which the apostle refers are those which he had specified in the previous part of the chapter, and which he had spoken of as so evil in their nature, and so dangerous in their tendency. The word rendered “be afflicted” means, properly, to endure toil or hardship; then to endure affliction or distress; and here means, that they were to afflict themselves - that is, they were to feel distressed and sad on account of their transgressions. Compare Ezra 8:21. The other words in this clause are those which are expressive of deep grief or sorrow. The language here used shows that the apostle supposed that it was possible that those who had done wrong should voluntarily feel sorrow for it, and that, therefore, it was proper to call upon them to do it.
(All who feel true sorrow for sin, do so voluntarily; but it is not intended by this assertion to insinuate that repentance is not the work of the Spirit. He operates on men without destroying their freedom, or doing violence to their will: “in the day of his power they are willing.” Nor is it improper to call on men to do that for which they require the Spirit’s aid. That aid is not withheld in the hour of need; and everywhere the Bible commands sinners to believe and repent.)
Let your laughter be turned to mourning - It would seem that the persons referred to, instead of suitable sorrow and humiliation on account of sin, gave themselves to joyousness, mirth, and revelry. See a similar instance in Isaiah 22:12-13. It is often the case, that those for whom the deep sorrows of repentance would be peculiarly appropriate, give themselves to mirth and vanity. The apostle here says that such mirth did not become them. Sorrow, deep and unfeigned, was appropriate on account of their sins, and the sound of laughter and of revelry should be changed to notes of lamentation. To how many of the assemblies of the vain, the gay, and the dissipated, might the exhortation in this passage with propriety be now addressed!
Your joy to heaviness - The word here rendered heaviness occurs nowhere else in the New Testament. It means dejection, sorrow. It is not gloom, melancholy, or moroseness, but it is sorrow on account of sin. God has so made us that we should feel sorrow when we are conscious that we have done wrong, and it is appropriate that we should do so.