Adam Clarke's Commentary on the Bible

Verse 6 (2 Peter 2:6)

The cities of Sodom and Gomorrha - See the notes on Genesis 19 (note), for an account of the sin and punishment of these cities.

Making them an ensample - These three words, ὑποδειγμα, παραδειγμα , and δειγμα , are used to express the same idea; though the former may signify an example to be shunned, the second an example to be followed, and the third a simple exhibition. But these differences are not always observed.

- Adam Clarke's Commentary on the Bible