Matthew Poole and continuators on 2 Peter 2:4

4 For if God spared not the angels that sinned, but cast them down to hell , and delivered them into chains of darkness , to be reserved unto judgment .

Elsewhere called the Deep, Luke, 8.31. and the botcomless-Pit, Rev. 9.1. and 11.7. and 17.8. and 20.1, 3. This implies a change, 1. Of the state of those Sinning Angels, that whereas before it was the highest among the Creatures, now it is the lowest. 2. Of their place, that whereas they were before the Throne of God with the rest of the Angels, they are now thrust down into a lower place, agreeable to their Sin and Misery. What place that is we find not expressed in Scripture; and therefore we are not to be over-curious in our enquiries after it; but may rest satisfied, that they are excluded from the place of their primitive Happiness; and are in a place, where they are afflicted with the pain both of loss and sence.

Either to be bound, or held with Darkness as with Chains; or kept in Chains under Darkness, as Iude 6. where Darkness may imply the misery and horror of their condition, and Chains, their obduration in their wickedness, their despair of Deliverance, their expectation of future Judgment, (Heb. 10.27.) together with the Providence and Power of God, watching over, and holding them in that condition, till final Vengeance come upon them. It is a Metaphor taken from Malefactors Condemned, who are bound in Chains, and kept in the Dungeon till Execution.

So kept that they cannot escape.

Viz. That of the Last-Day, the time of their full Torment, in which the Wrath of God which they feel in a great measure now, will come upon them to the utmost.

Marginal references: Job 4.18.; Joh. 8.44.