Then I saw an angel coming down from heaven, holding in his hand the key of the abyss and a heavy chain.
He seized the dragon, that ancient serpent - that is, the Devil, or Satan - and chained him up for a thousand years. 1
References for Revelation 20:2
The angel threw him into the abyss, locked it, and sealed it, so that he could not deceive the nations any more until the thousand years were over. After that he must be set loose for a little while.
Then I saw thrones, and those who sat on them were given the power to judge. I also saw the souls of those who had been executed because they had proclaimed the truth that Jesus revealed and the word of God. They had not worshiped the beast or its image, nor had they received the mark of the beast on their foreheads or their hands. They came to life and ruled as kings with Christ for a thousand years. 2
References for Revelation 20:4
20.4 Dn 7.9, 22.
(The rest of the dead did not come to life until the thousand years were over.) This is the first raising of the dead.
Happy and greatly blessed are those who are included in this first raising of the dead. The second death has no power over them; they shall be priests of God and of Christ, and they will rule with him for a thousand years.