2 Peter 2:4

Amplified Bible

⁴^[a]For if God did not [even] spare angels that sinned, but threw them into ^[b]hell and sent them to pits of gloom to be kept [there] for judgment;

2 Peter 2:4 This verse begins one of the longest sentences in the NT. The sentence concludes in v 10a.
2 Peter 2:4 For emphasis Peter uses a word (tartarus) from Greek mythology describing a hell reserved for the most horrendous of people to emphasize the terrible doom awaiting false prophets and teachers who manipulate and twist the truth of the gospel message.