(Rev. 20:4 KJV) 4 And I saw thrones, and they sat upon them, and judgment was given unto them: and I saw the souls of them that were beheaded for the witness of Jesus, and for the word of God, and which had not worshipped the beast, neither his image, neither had received his mark upon their foreheads, or in their hands; and they lived and reigned with Christ a thousand years.
A Seal Upon Him
(Rev. 20:3 KJV) 3 And cast him into the bottomless pit, and shut him up, and set a seal upon him, that he should deceive the nations no more, till the thousand years should be fulfilled: and after that he must be loosed a little season.
Satan is cast into prison and the door is locked and sealed. The seal shows that he can’t open the door because it’s by God’s authority that he’s bound. He can’t deceive the nations until the end of the 1000 years.