Theodoret of Cyrus
Initially, the Ammonites and Moabites launched an attack against the Edomites, and soon after, they turned their aggression upon one another. The king and his subjects observed the devastation of their foes.
For the children of Ammon, and of Moab, rose up against the inhabitants of mount Seir, to kill and destroy them: and when they had made an end of them, they turned also against one another, and destroyed one another.
וַ֠יַּֽעַמְדוּ בְּנֵ֨י עַמּ֧וֹן וּמוֹאָ֛ב עַל־יֹשְׁבֵ֥י הַר־שֵׂעִ֖יר לְהַחֲרִ֣ים וּלְהַשְׁמִ֑יד וּכְכַלּוֹתָם֙ בְּיוֹשְׁבֵ֣י שֵׂעִ֔יר עָזְר֥וּ אִישׁ־בְּרֵעֵ֖הוּ לְמַשְׁחִֽית׃
One Church Father comments on this verse
Initially, the Ammonites and Moabites launched an attack against the Edomites, and soon after, they turned their aggression upon one another. The king and his subjects observed the devastation of their foes.
Passages read together with this verse.