Nahum 1 Is a sobering reminder that Yahuah's mercy is not unconditional.

Several decades before Nahum's prophecy, the prophet Jonah had approached Nineveh, the capital of the Assyrian empire, warning them to repent. The people of Nineveh had heeded Jonah's message and repented, averting Yahuah's judgment at that time.

However, years later, the Assyrians under leaders like Shalmaneser and Sargon II conquered the northern kingdom of Israel, exiling the 10 tribes in what is known as the Assyrian captivity around 722 BCE.

Decades after this, during the reign of Assyrian king Sennacherib (705-681 BCE), Nahum delivers his prophecy foretelling Yahuah's impending judgment and destruction upon Nineveh for their violence, idolatry and oppression of Yahuah's people.

So while Nineveh had temporarily repented during Jonah's time, they later returned to their wicked ways, subjugating Israel and other nations. Yahuah, being long-suffering yet just, decreed through Nahum that Nineveh's reprieve was over - they would face His wrath for failing to maintain repentance and continuing in evil against His people.

Nahum's message served as a sobering reminder that Yahuah's mercy is not unconditional. Genuine, lasting repentance was required, not mere temporary remorse, to escape His righteous judgment upon the unrepentant.