I looked, and there before me was a white cloud, and seated on the cloud was one like a son of man with a crown of gold on his head and a sharp sickle in his hand. Then another angel came out of the temple and called in a loud voice to him who was sitting on the cloud, “Take your sickle and reap, because the time to reap has come, for the harvest of the earth is ripe.” So he who was seated on the cloud swung his sickle over the earth, and the earth was harvested.Revelation 14:14-16 NIV
This extended passage, verses 14-20, is similar, although not identical, to the parable of the wheat and the tares found in Matthew 13:24-30. In that parable there are two harvests, one to gather the wheat and one to gather the weeds to be burned. They represented two resurrections, one of believers to heaven and the other of unbelievers to judgement.
Here, verses 14-16 describe the first of two harvests, this one starting with someone sitting on a white cloud wearing a golden crown and holding a sharp sickle. Who is this? John described him as ‘like a son of man‘, a favorite description of Jesus for himself. So it would seem to be Jesus, coming on a cloud (Matt. 24:30, Acts 1:9-11), coming to gather his elect from across the world (Matt. 24:31). And when does he come? When the harvest is fully ripe. We don’t know when that will be, But God does and is patiently waiting (2 Pet. 3:8-9) for the harvest to be ready. While we wait for this reaping, we should also continue to labor in the fields (Matt. 9:35-38), working to increase the harvest.