Rev 14:14-16
"Then I looked, and behold, a white cloud, and seated on the cloud one like a son of man, with a golden crown on his head, and a sharp sickle in his hand. And another angel came out of the temple, calling with a loud voice to him who sat on the cloud, ‘Put in your sickle, and reap, for the hour to reap has come, because the harvest of the earth is fully ripe.’"
The double harvest: the reaping (salvation of the saints) and the vintage (judgment of the wicked). Christ as the reaper — the image of Mt 13:39-43 expanded. The harvest is the end of history — the final separation between those who belong to Christ and those who belong to the world.