The Lord of hosts hath sworn by himself. — This is, as in Jeremiah 49:13; Amos 6:8, the most solemn form of affirmation. Compare Hebrews 6:13, and Note on Jeremiah 49:13.
Surely I will fill thee with men, as with Caterpillers. — Better, with grasshoppers or locusts, the fullest type of the swarms of the destroyer (Nahum 3:15). The “Surely” answers to the Hebrew “For if,” as giving the condition on which the shouting depends.
They shall lift up a shout against thee. — The thought is the same as in Jeremiah 25:30. The “shout” is that of those who tread the grapes in the wine-press, and that, as in Isaiah 63:2-3, is the received symbol of conquest and destruction.