Jamieson, Fausset and Brown on Revelation 20:1

CHAPTER 20

Re 20:1-15. Satan Bound, and the First-Risen Saints Reign with Christ, a Thousand Years; Satan Loosed, Gathers the Nations, Gog and Magog, Round the Camp of the Saints, and Is Finally Consigned to the Lake of Fire; the General Resurrection and Last Judgment.

1. The destruction of his representatives, the beast and the false prophet, to whom he had given his power, throne, and authority, is followed by the binding of Satan himself for a thousand years.

the key of the bottomless pit--now transferred from Satan's hands, who had heretofore been permitted by God to use it in letting loose plagues on the earth; he is now to be made to feel himself the torment which he had inflicted on men, but his full torment is not until he is cast into "the lake of fire" (Re 20:10).