The same holds good, by reason of this number twelve, of those that are to be judged. For when it is said, “Judging the twelve tribes,” yet is not the tribe of Levi, which is the thirteenth, to be exempt from being judged by them; nor shall they judge this nation alone, and not also other nations.
Reproduced in full. Translation: Oxford 1841 (Newman), public domain (Public domain).
Also cites: City of God, book xx, ch. 5