1 Peter 3:19

in which also he went and preached to the spirits in prison,

1 Peter 4:6

For to this end was the gospel preached also to the dead, that they might indeed be judged according to men in the flesh, but might live according to God in the spirit.

1 Peter 1:11-12

searching what or what manner of time the Spirit of Christ which was in them signified, when it testified beforehand the sufferings to come upon Christ, and the glories that were to follow;

Revelation 19:10

And I fell at his feet to worship him; and he saith to me, See thou do it not; I am a fellowservant of thee, and of thy brethren who maintain the testimony to Jesus; worship God. For the testimony to Jesus is the spirit of prophecy.

Revelation 20:7

And when the thousand years are ended, Satan will be loosed out of his prison;

Treasury of Scripture Knowledge

Summary

By which also he went and preached unto the spirits in prison;

Bible References

By which

1 Peter 1:11
searching what or what manner of time the Spirit of Christ which was in them signified, when it testified beforehand the sufferings to come upon Christ, and the glories that were to follow;
1 Peter 4:6
For to this end was the gospel preached also to the dead, that they might indeed be judged according to men in the flesh, but might live according to God in the spirit.
Revelation 19:10
And I fell at his feet to worship him; and he saith to me, See thou do it not; I am a fellowservant of thee, and of thy brethren who maintain the testimony to Jesus; worship God. For the testimony to Jesus is the spirit of prophecy.

In

Revelation 20:7
And when the thousand years are ended, Satan will be loosed out of his prison;