Albert Barnes Commentary Isaiah 17:13

"The nations shall rush like the rushing of many waters: but he shall rebuke them, and they shall flee far off, and shall be chased as the chaff of the mountains before the wind, and like the whirling dust before the storm." — Isaiah 17:13 (ASV)

God shall rebuke them - The word ‘God’ is not here in the original, but is evidently to be supplied. The word ‘rebuke’ means that He would disarrange their plans, prevent their success, and defeat their purposes. It shows the great power of God, that He can thus by a “rebuke” - a word - arrest mighty nations, and discomfit them when they are tumultuously hastening onward in the confidence of victory. This discomfiture refers, doubtless, to the overthrow of Sennacherib and his army by the pestilence (2 Kings 19:35; see the notes at Isaiah 37:36).

And they shall flee far off - The whole army of Sennacherib was not destroyed, but a part returned with him to Assyria (2 Kings 19:36).

And shall be chased as the chaff ... - Denoting the ease with which God would do it, and the certain and entire discomfiture of the army. The figure is one that is very striking in describing an army that is routed, and that flees in disorder (Psalms 1:4; Psalms 35:5; Isaiah 29:5; Hosea 13:3).

And like a rolling thing - Margin, ‘Thistle-down.’ It means, literally, anything that “rolls” (גלגל galgal — from גלל gâlal — to roll). It is applied to chaff, stubble, or anything that is driven about by a whirlwind (Psalms 83:14).