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 anger is quite an intriguing facet of this narrative. Picture it: a prophet who escapes to avoid delivering a divine message, only to sulk when the very folks he wishes ill upon turn from their ways and find mercy. It's almost a dramatic twist worthy of a soap opera! Instead of rejoicing, Jonah sits fuming on a hillside, wanting his prophecy of destruction to come true. His attitude underscores a deeper human flaw: sometimes our own expectations and prejudices cloud our understanding of grace.

It’s fascinating to note that the city of Nineveh, with its vast population, embraced a genuine turnaround — king to cattle, everyone joined in mourning their misdeeds. In the ancient Near East, Nineveh was the epicenter of wealth and power, yet here lay a quintessential truth: repentance draws God’s mercy, regardless of one’s past. Jonah’s discontent highlights a significant moral conundrum, questioning what it means to accept unconditional mercy.

Moreover, Jonah's internal struggle reveals he's not entirely alone; throughout the biblical narrative, many characters grapple with understanding divine justice versus mercy (just think of Job and his frustrations). This interplay of emotions makes Jonah not merely a tale of a big fish but a resonant story reminding us to reflect on our reactions to the mercy granted to others, encouraging a broader understanding of compassion in our lives.