Now when the thousand years have expired, Satan will be released from his prison
Revelation 20:7
Surrounding context
20:6 Blessed and holy is he who has part in the first resurrection. Over such the second death has no power, but they shall be priests of God and of Christ, and shall reign with Him a thousand years.
20:7 Now when the thousand years have expired, Satan will be released from his prison
20:8 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.