Theodoret of Cyrus
Seir is a mountain belonging to Idumea, as previously mentioned. The Idumeans, who are descendants of Esau, held deep-seated animosity towards the Jewish people, and thus they took pleasure in the misfortunes that afflicted them. In response to this, the Sovereign Lord declares a final judgement against them. When He states, My hand will stretch out My hand against you, it serves as a metaphor for profound wrath, drawing upon the imagery of those who strike with their hands. It is important to recognize that God's nature is one of passion, and such expressions in Scripture are tailored to resonate with the capabilities of the audience. Following this proclamation of judgement, God also reveals the justification for it.