Revelation 20:1 And I saw an angel come
down from heaven, having the key of the bottomless pit
and a great chain in his hand.
2 And he laid hold on the dragon, that
old serpent, which is the Devil, and Satan, and bound
him a thousand years,
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.
The fallen angels had been cast out of
heaven, with the devil, back in chapter 12:
Revelation 12:9 And the great dragon
was cast out, that old serpent, called the Devil, and
Satan, which deceiveth the whole world: he was cast out
into the earth, and his angels were cast out with him.