Heidegger's Bible Handbook: Nahum: Argument

2.  The argument of the Prophecy.  It contains diplomatic letters to be sent to Sennacherib.

The argument of the book is the מַשָּׂ֖א נִֽינְוֵ֑ה, the burden or sentence of Nineveh, Nahum 1:1, that is, the word of God set forth against Nineveh.  More specifically, the Prophet, asserting the most mighty administration of God for His own and against His enemies, denounces destruction agains Sennacherib, Nineveh, and the whole Kingdom of the Assyrians.  He feigns diplomatic letters to have been written by God and sent to the Assyrians, wherein war is declared against them, and it is shown how powerful and terrible is that God as an enemy of the Ninevites; he also depicts the reasons for the destruction, even cruelty and idolatry, and confirms the previously related law from the example of idolatry:  to all, the highest and lowest, he foretells dejection of soul, dishonorable flight, conflagrations, and indiscriminate slaughters.  He also repeatedly inserts promises concerning the people of God.