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 in chapter 4 really highlights his profound internal struggle and the complexities of human emotions, especially when it comes to justice and mercy. Picture it: here’s a guy who has literally been swallowed by a giant fish, spat back out, and taken on the daring task of delivering God’s message to Nineveh — a city notoriously wicked. You can imagine Jonah itching for divine retribution against a people he deemed deserving of destruction.

But when the Ninevites genuinely repent and God spares them, Jonah's over-the-top anger reveals a greater lesson about forgiveness and the expansiveness of divine compassion. It’s interesting to note that Jonah’s name means "dove", traditionally a symbol of peace and hope. The irony doesn't escape a thoughtful reader; instead of spreading peace, he stands brooding outside the city, wishing for its doom.

It’s also worth pondering Jonah’s contrasting storyline to the parable of the prodigal son in the New Testament. In both narratives, there’s a serious challenge to the accepted norms of justice; both show how radically God's grace operates outside of human expectations.

Furthermore, Jonah plants himself at the outskirts of the town, hoping perhaps to still see that destruction. While he's there with a front-row seat to grace, he's not ready to accept this new narrative of divine love. It’s a pretty worthwhile reflection on how we often resist change or broader definitions of mercy in our own lives.