1 Enoch 10:6
4 And again the Lord said to Raphael: 'Bind Azâzêl hand and foot, and cast him into the darkness: and make an opening in the desert, which is in Dûdâêl, and cast him therein. 5 And place upon him rough and jagged rocks, and cover him with darkness, and let him abide there for ever, and cover his face that he may not see light. 6 And on the day of the great judgement he shall be cast into the fire. And heal the earth which the angels have corrupted, and proclaim the healing of the earth, that they may heal the plague, and that all the children of men may not perish through all the secret things that the Watchers have disclosed and have taught their sons. 8 And the whole earth has been corrupted through the works that were taught by Azâzêl: to him ascribe all sin.' 9 And to Gabriel said the Lord: 'Proceed against the bastards and the reprobates, and against the children of fornication: and destroy [the children of fornication and] the children of the Watchers from amongst men [and cause them to go forth]: send them one against the other that they may destroy each other in battle: for length of days shall they not have.
Jude 1:6
4 For certain men have secretly slipped in among you—men who long ago were marked out for the condemnation I am about to describe—ungodly men who have turned the grace of our God into a license for evil and who deny our only Master and Lord, Jesus Christ. 5 Now I desire to remind you (even though you have been fully informed of these facts once for all) that Jesus, having saved the people out of the land of Egypt, later destroyed those who did not believe. 6 You also know that the angels who did not keep within their proper domain but abandoned their own place of residence, he has kept in eternal chains in utter darkness, locked up for the judgment of the great Day. 7 So also Sodom and Gomorrah and the neighboring towns, since they indulged in sexual immorality and pursued unnatural desire in a way similar to these angels, are now displayed as an example by suffering the punishment of eternal fire.
Notes and References
"... Similarly, prior to this quotation, God, having been informed of the Watchers' sexual transgressions, commands that the angels endure punishments similar to those that Jude succinctly presents (1 Enoch 10). Based on these parallels, it is reasonable that Jude is summarizing the Enochic legend of the Watchers, referring not only to their Divine judgment, but the sexual sin that led to it. The final summary in the reminder builds upon an ancient, well-established pattern of referring to Sodom and Gomorrah as paradigms of God's judgment. Jude falls in line with tradition and notes that the cities serve as an example by undergoing the punishment of eternal fire ..."
Hunt, Benjamin B. "Know Your Enemies": Rhetorical Semantics in the Epistle of Jude (p. 97) McMaster Divinity College, 2014