THE name of this prophet signifies a comforter; for it was a charge given to all the prophets, Comfort you, comfort you, my people: and even this prophet, though wholly taken up in foretelling the destruction of Nineveh, which speaks terror to the Assyrians, is, even in that, comforter to the ten tribes of Israel, who, it is probable, were now lately carried captives into Assyria. It is very uncertain at what time he lived and prophesied, but it is most probable that he lived in the time of Hezekiah, and prophesied against Nineveh, after the captivity of Israel by the king of Assyria, which was in the ninth year of Hezekiah, and before Sennacherib’s invading Judah, which was in the fourteenth year of Hezekiah, for to that attempt, and the defeat of it, it is supposed, the first chapter has reference; and it is probable that it was delivered a little before it, for the encouragement of God’s people in that day of treading down and perplexity.
It is the conjecture of the learned Huetius that the two other chapters of this book were delivered by Nahum some years after, perhaps in the reign of Manasseh, and in that reign the Jewish chronologies generally place him, somewhat nearer to the time when Nineveh was conquered, and the Assyrian monarchy reduced, by Cyaxares and Nebuchadnezzar, some time before the first captivity of Judah. It is probable that Nahum did by word of mouth prophesy many things concerning Israel and Judah, as it is certain that Jonah did (2 Kings xiv. 25), though we have nothing of either of them in writing, but what related to Nineveh, of which though a great and ancient city, yet probably we should never have heard in sacred writ if the Israel of God had not had some concern in it.
– Matthew Henry Commentary