1 Peter 3:19

(It was in the Spirit that Enoch also went and preached to the imprisoned spirits

1 Peter 4:6

(for this was why the gospel was preached to the dead as well, that while they are judged in the flesh as men, they may live as God lives in the spirit).

1 Peter 1:11-12

the Spirit of messiah within them foretold all the suffering of messiah and his after-glory, and they pondered when or how this was to come;

Revelation 19:10

Then I fell before his feet to worship him; but he said to me, "No, not that! I am but a servant like yourself and your brothers, who hold the testimony of Jesus. Worship God" (for the testimony borne by Jesus is the breath of all prophecy).

Revelation 20:7

But when the thousand years are over, Satan will be released from 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
the Spirit of messiah within them foretold all the suffering of messiah and his after-glory, and they pondered when or how this was to come;
1 Peter 4:6
(for this was why the gospel was preached to the dead as well, that while they are judged in the flesh as men, they may live as God lives in the spirit).
Revelation 19:10
Then I fell before his feet to worship him; but he said to me, "No, not that! I am but a servant like yourself and your brothers, who hold the testimony of Jesus. Worship God" (for the testimony borne by Jesus is the breath of all prophecy).

In

Revelation 20:7
But when the thousand years are over, Satan will be released from his prison,