Demons (evil spirits) were afraid that Jesus
would cast them into the Abyss or Bottomless
Pit.

Luke 8:31"And they besought Him that He
would not command them to go out into the
deep".

We do not know if Jesus ever cast them into
the Pit. They insisted that their time had not
come. (Matt. 8:29)

But Satan and his Demons will eventually be
locked up in the Bottomless Pit at the end of
the age. They will not be able to deceive any
more until the end of the thousand year reign
of Jesus Christ. (Rev. 20:1-3)

Rev. 9:1-3 and Jude 6 tell us that there are
demons already confined but many are roaming
the earth. They know that they must obey the
authority of Jesus or face the punishment
(the Pit) which they are afraid to go.