A.T. Robertson Commentary 2 Peter 2:6

"and turning the cities of Sodom and Gomorrah into ashes condemned them with an overthrow, having made them an example unto those that should live ungodly;" — 2 Peter 2:6 (ASV)

Turning into ashes (τεφρωσας). First aorist participle of τεφροω, late word from τεφρα, ashes (in Dio Cassius of an eruption of Vesuvius, Philo), here alone in N.T.

The cities of Sodom and Gomorrah (πολεις Σοδομων κα Γομορρας). Genitive of apposition after πολεις (cities), though it makes sense as possessive genitive, for Jude 1:7 speaks of the cities around these two. The third example, the cities of the plain. See Ge 19:24f.

Condemned them (κατεκρινεν). First aorist active indicative of κατακρινω, still part of the protasis with ε.

With an overthrow (καταστροφη). Instrumental case or even dative like θανατω with κατακρινω in Mt 20:18. But Westcott and Hort reject the word here because not in B C Coptic.

Having made them (τεθεικως). Perfect active participle of τιθημ.

An example (υποδειγμα). For which see Jas 5:10; John 13:15. Cf. 1 Peter 2:21.

Unto those that should live ungodly (μελλοντων ασεβεσιν). Rather, "unto ungodly men of things about to be" (see Heb 11:20 for this use of μελλοντων). But Aleph A C K L read ασεβειν (present active infinitive) with μελλοντων=ασεβησοντων (future active participle of ασεβεω), from which we have our translation.