Behold, the Lord hath a mighty and strong one - The Hebrew of this passage is, ‘Lo! there is to the Lord (לאדני la'donāy) mighty and strong.’ Lowth renders it,
‘Behold the mighty one, the exceedingly strong one,’
And supposes that it means the Lord himself. It is evident, however, that something must be understood as being that which the Lord ‘hath,’ for the Hebrew properly implies that there is something strong and mighty which is under his control, and with which, as with a tempest, he will sweep away and destroy Ephraim. Jarchi supposes that רוח rûach (“wind”) is understood; Kimchi thinks that the word is יום yôm (“day”); others believe that חיל chayil (“an army”) is understood. But I think the obvious interpretation is to refer it to the Assyrian king, as the agent by which Yahweh would destroy Samaria 2 Kings 17:3-6. This power was entirely under the direction of Yahweh, and would be employed by him in accomplishing his purpose on that guilty people (compare the notes at Isaiah 10:5-6).
As a tempest of hail - A storm of hail is a most striking representation of the desolation that is produced by the ravages of an invading army (compare Job 27:21; the note at Isaiah 30:30; also Hosea 13:15).
A flood of mighty waters - This is also a striking description of the devastating effects of an invading army (compare Psalms 90:5; Jeremiah 46:7-8)
Shall cast down to the earth - To cast it to the earth means that it should be entirely humbled and destroyed (see the note at Isaiah 25:12).
With the hand - Septuagint: βίᾳ bia - ‘Force,’ ‘violence.’ This is its meaning here; as if it were taken in the hand, like a cup, and dashed indignantly to the ground.