Charles Ellicott Commentary Judges 5:4

"Jehovah, when thou wentest forth out of Seir, When thou marchedst out of the field of Edom, The earth trembled, the heavens also dropped, Yea, the clouds dropped water." — Judges 5:4 (ASV)

Lord, when thou wentest out of Seir. —See Psalms 68:7-9; Habakkuk 3:3–12. The majority of commentators, both ancient and modern, suppose that the reference is to the promulgation of the law on Sinai, as described in Exodus 19:16-18, Deuteronomy 33:3. But the mention of Seir and Edom seems to show that this is not the case, and, indeed, the imagery is different, and the context requires a more pertinent allusion.

If the thunders and lightnings of the fiery law are alluded to, we can only suppose that a contrast is intended between the glory which Israel derived from that revelation and their recent abject condition.

However, the train of thought is clearer if we explain the allusion as referring to the march of Israel from Kadesh Barnea to their first great conquest on the east of the Jordan. This march seems to have been signalised, and the battles of Israel aided, by the same majestic natural phenomena as those which had helped them to defeat Sisera, as though Jehovah Himself were the leader of their vanguard. Though the earthquakes and rains which made so deep an impression upon them are not recorded in the Pentateuch, the memory of the circumstances is preserved in these three passages.