John Calvin on Joel 3:12

The Prophet proceeds with the same subject, — that God will at length become an avenger of the wrongs of his people, when they shall be unjustly harassed by profane men. We indeed know that God does not immediately succor his servants but rests as though he did not regard their troubles; but this he does to try their patience; and then at a suitable time he declares that he had not been indifferent, but had noticed the evils done to them, and deferred punishment until the wickedness of his enemies had been completed. So he says now, that God will at length be the defender of his people against all the nations assembled from every quarter in the valley of Jehoshaphat. Of this valley we have said enough already. But the chief thing is, that the afflictions of the Church shall not go unpunished; for God at the right time will ascend his tribunal, and cause all nations from every part of the earth to assemble and to be there judged. Now it follows —

Joel 3:13

13. Put ye in the sickle, for the harvest is ripe: come, get you down; for the press is full, the fats overflow; for their wickedness is great.

13. Mittite falcem, quia maturuit messis: venite, descendite, quia plenum est torcular, refertae sunt cuppae, quia multiplicata est malitia ipsorum.