When thou wentest out of Seir - Here is an allusion to the giving of the law, and the manifestation of God's power and glory at that time; and as this was the most signal display of his majesty and mercy in behalf of their forefathers, Deborah very properly begins her song with a commemoration of this transaction.
Compare Psalm 68:7-9, and Habakkuk 3:3-16. The three passages relate to the same events, and mutually explain each other. The subject of them is the triumphant march of Israel, with the Lord at their head, to take possession of Canaan, and the overthrow of Sihon, Og, and the Midianites. This march commenced from Kadesh, in the immediate neighborhood of Self, and the victories which followed were an exact parallel to the victory of Deborah and Barak, accompanied as it had been with the storm which made Kishon to overflow his banks.