The river of Kishon {q} swept them away, that ancient river, the river Kishon. O my soul, thou hast trodden down strength.

(q) As a broom does to the filth of the house.

Wesley's Notes

5:21 River of Kishon - Which, though not great in itself, was now much swelled by the foregoing storm and rain, and therefore drowned those who being pursued by the hand of God, and by the Israelites, were forced into it, and thought to pass over it, as they did before. Ancient river - So called, either, first, in opposition to those rivers which are of a later date, being made by the hand and art of man. Or, secondly, because it was a river anciently famous for remarkable exploits, for which it was celebrated by the ancient poets or writers, though not here mentioned. Trodden down - Thou, O Deborah, though but a weak woman, hast by God's assistance subdued a potent enemy. Such abrupt speeches are frequent in poetical scriptures.

Jamieson-Fausset-Brown Bible Commentary

21. the river of Kishon swept them away-The enemy was defeated near "the waters of Megiddo"-the sources and side streams of the Kishon: they that fled had to cross the deep and marshy bed of the torrent, but the Lord had sent a heavy rain-the waters suddenly rose-the warriors fell into the quicksands, and sinking deep into them, were drowned or washed into the sea [Van De Velde].

Matthew Henry's Concise Commentary

5:12-23 Deborah called on her own soul to be in earnest. He that will set the hearts of other men on fire with the love of Christ, must himself burn with love. Praising God is a work we should awake to, and awake ourselves unto. She notices who fought against Israel, who fought for them, and who kept away. Who fought against them. They were obstinate enemies to God's people, therefore the more dangerous. Who fought for them. The several tribes that helped are here spoken of with honour; for though God is above all to be glorified, those who are employed must have their due praise, to encourage others. But the whole creation is at war with those to whom God is an enemy. The river of Kishon fought against their enemies. At most times it was shallow, yet now, probably by the great rain that fell, it was so swelled, and the stream so deep and strong, that those who attempted to pass, were drowned. Deborah's own soul fought against them. When the soul is employed in holy exercises, and heart-work is made of them, through the grace of God, the strength of our spiritual enemies will be trodden down, and will fall before us. She observes who kept away, and did not side with Israel, as might have been expected. Thus many are kept from doing their duty by the fear of trouble, the love of ease, and undue affection to their worldly business and advantage. Narrow, selfish spirits care not what becomes of God's church, so that they can but get, keep, and save money. All seek their own, Php 2:21. A little will serve those for a pretence to stay at home, who have no mind to engage in needful services, because there is difficulty and danger in them. But we cannot keep away from the contest between the Lord and his enemies; and if we do not actively endeavour to promote his cause in this wicked world, we shall fall under the curse against the workers of iniquity. Though He needs no human help, yet he is pleased to accept the services of those who improve their talents to advance his cause. He requires every man to do so.