LXX Job 40:20
16 Behold now, his strength is in his loins, and his force is in the navel of his belly. 17 He sets up his tail like a cypress; and his nerves are wrapped together. 18 His sides are sides of brass; and his backbone is as cast iron. 19 This is the chief of the creation of the Lord; made to be played with by his angels. 20 And when he has gone up to a steep mountain, he causes joy to the quadrupeds in Tartarus. 21 He lies under trees of every kind, by the papyrus, and reed, and bulrush. 22 And the great trees make a shadow over him with their branches, and so do the bushes of the field.
2 Peter 2:4
2 And many will follow their debauched lifestyles. Because of these false teachers, the way of truth will be slandered. 3 And in their greed they will exploit you with deceptive words. Their condemnation pronounced long ago is not sitting idly by; their destruction is not asleep. 4 For if God did not spare the angels who sinned, but threw them into Tartarus16 and locked them up in chains in utter darkness, to be kept until the judgment, 5 and if he did not spare the ancient world, but did protect Noah, a herald of righteousness, along with seven others, when God brought a flood on an ungodly world, 6 and if he turned to ashes the cities of Sodom and Gomorrah when he condemned them to destruction, having appointed them to serve as an example to future generations of the ungodly,
Notes and References
"... The verbs “to cast into Tartarus,” and were almost always used with reference to the early Greek theogonic myths, in which the ancient giants, the Cyclopes and Titans, were imprisoned in Tartarus, the lowest part of the underworld, by Uranos, Kronos and Zeus. They are not used in the Greek version of 1 Enoch; though τάρταρος (“Tartarus”) is used of the place of divine punishment in 1 Enoch 20:2, as elsewhere in Jewish Greek literature (LXX Job 40:20; 41:24; Proverbs 30:16; Sibylline Oracles 4:186; Philo, Life of Moses 2.433). But Hellenistic Jews were aware that the Greek myth of the Titans had some similarity to the fall of the Watchers (though Philo, Gig. 58, rejects any comparison). Sometimes the Watchers’ sons, the giants (the Nephilim), were compared with the Titans (Josephus, Antiquities 1.73; cf. LXX Ezekiel 32:27; Sirach 16:7) but in Judith 16:6 (and also the Christian passage Sibylline Oracles 2:231) the Watchers themselves seem to be called τιτᾶνες (“Titans”). Thus in using a term reminiscent of the Greek myth of the Titans the author of 2 Peter follows Hellenistic Jewish practice ..."
Bauckham, Richard Word Biblical Commentary: Jude-2 Peter (pp. 249-250) Zondervan, 1983