47 “Again, the kingdom of heaven is like a dragnet that was cast into the sea and gathered some of every kind,
48 which, when it was full, they drew to shore; and they sat down and gathered the good into vessels, but threw the bad away.
49 So it will be at the end of the age. The angels will come forth, separate the wicked from among the just,
50 and cast them into the furnace of fire. There will be wailing and gnashing of teeth.”
51 Jesus said to them, “Have you understood all these things?” They said to Him, “Yes, Lord.”
dragnet (v.47) — the largest kind of net, weighed below with corks on top, sweeping perhaps a half mile of water. Because of its large character, the net collects a multitude of different kinds of fish, described in the text as “every kind.” Nets of this size were too large to empty into a boat and had to be drawn to shore. Here the fish were sorted. Those that were bad, or for any reason unusable, were cast back into the sea. — Walvoord, page 106
Although the commentaries state that these events will take place when the Lord returns at the beginning of the Millennium, I think they are a perfect description of what happens at the end of the Millennium as described in Revelation 20:12-15. (I’ll give a few earlier verses as context.)
7 Now when the thousand years have expired, Satan will be released from his prison
8 and will go out to deceive the nations which are in the four corners of the earth, Gog and Magog, to gather them together to battle, whose number is as the sand of the sea.
9 They went up on the breadth of the earth and surrounded the camp of the saints and the beloved city. And fire came down from God out of heaven and devoured them.
10 The devil, who deceived them, was cast into the lake of fire and brimstone where the beast and the false prophet are. And they will be tormented day and night forever and ever.
11 Then I saw a great white throne and Him who sat on it, from whose face the earth and the heaven fled away. And there was found no place for them.
12 And I saw the dead, small and great, standing before God, and books were opened. And another book was opened, which is the Book of Life. And the dead were judged according to their works, by the things which were written in the books.
13 The sea gave up the dead who were in it, and Death and Hades delivered up the dead who were in them. And they were judged, each one according to his works.
14 Then Death and Hades were cast into the lake of fire. This is the second death.
15 And anyone not found written in the Book of Life was cast into the lake of fire.