NET
4 For if God did not spare the angels who sinned, but threw them into hell and locked them up in chains in utter darkness, to be kept until the judgment,
Darby
4 For if God spared not [the] angels who had sinned, but having cast them down to the deepest pit of gloom has delivered them to chains of darkness [to be] kept for judgment;
KJV
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;