The Son of Man is the one who reaps the first harvest of the saved. Although He is intimately involved with the first harvest, Scripture reveals that angels carry out the details of both harvests. the earth was reaped
The reaping which takes place is worldwide. And He will send His angels with a great sound of a trumpet, and they will gather together His elect from the four winds, from one end of heaven to the other (Mtt. Mat. 24:31). One view connects this event with the resurrection of the saved dead prior to the Millennial Kingdom (cf. Rev. Rev. 20:4+).
This, then, is our Lords return at the end of the tribulation to harvest the bodies of the saints who die during the tribulation (Rev. Rev. 14:13+) so as to reunite them with their souls, which, up to this point, will have been under the altar before God (Rev. Rev. 6:9+). This reaping is the gathering of the harvest into Christs barn (Mtt. Mat. 13:30). . . . The living redeemed will still be on earth, but the bodies of all deceased saints will have been resurrected and taken to Heaven. This addresses the state of all the saved during the tribulation.1The saints which remain alive at the end of the Tribulation participate in the Sheep and Goat Judgment and enter the Millennial Kingdom in their natural bodies (Mtt. Mat. 25:31-34).
1 Monty S. Mills, Revelations: An Exegetical Study of the Revelation to John (Dallas, TX: 3E Ministries, 1987), Rev. 14:16.