Wo to the multitude ... - The word ‘woe’ (הוי hôy) may be either an interjection simply directing the attention to them, or it may be a word indicating approaching calamity and judgment (see the note at Isaiah 5:6). Gesenius supposes that it is rather the language of compassion, on account of the evil which they threatened to bring upon the people of God, like 1 Kings 13:30, ‘Ah! wo, my brother!’
The multitude of many people - Or, the tumult of many nations - a description of the noise attending an invading army made up of many nations mingled together, such as was that of Sennacherib.
Which make a noise ... - This is a beautiful description of a vast army, and of the shouting, the tumult, the din, which attends its march. The same comparison occurs in Jeremiah 6:23; Psalms 65:7 (see Ezekiel 43:2; Revelation 1:15; Revelation 14:2; Revelation 19:6).
And to the rushing of nations - The rushing of mighty armies to conquest.