The answer is: He was angry

Jonah 4:1 - Jonah felt that they should still be destroyed. He thought he knew how to govern better than God.

Jonah’s fiery reaction not only exposes his personal disappointment but also brings forth a fascinating dynamic between humanity and the divine. After initially fleeing God’s call to go to Nineveh, Jonah eventually fulfills that mission only to be incensed by the city's response to his warning. The residents, fueled by genuine repentance, genuinely believe they could change their fate - a notion that abruptly collides with Jonah's preconceived sense of justice.

Here’s the kicker: Jonah wasn’t just a prophet with a personal grudge; he was grappling with profound theological implications about the nature of mercy and repentance. His anger brings to light the age-old struggle of communities and individuals refusing to embrace forgiveness, prompting questions that still cling to religious discourses today. Can change truly happen? Who deserves mercy?

What’s intriguing is that the city of Nineveh, with its extravagant sinfulness in Jonah's eyes, managed to soften by Jonah’s simple message. There’s a Biblical echo here of God's choosing the meek, worthless insiders instead of the presumed righteous ones. Similarly, in the New Testament, we see the same theme in Jesus's encounters with society's outcasts.

Lastly, the fish and the "great city of Nineveh" are important symbols that hinge on transformation. Those digging into Jonah’s story may also find humor in the fact that Jonah thought he'd trick God—only to discover that it’s really God calling the shots in the grand design of compassion.