4:9 - Then God said to Jonah, “Do you have good reason to be angry about the plant?” And he said, “I have good reason to be angry, even to death.”
God now asks Jonah for the second time if he has good reason to be angry and adds "about the plant". I imagine Jonah may have exploded in his answer, as God pushed him to his limits. Once again, when the One who knows all things asks a question, be careful how you answer. In this case, Jonah cannot hold back. Jonah wishes he were dead because his shade plant died...
4:10 - Then the Lord said, “You had compassion on the plant for which you did not work and which you did not cause to grow, which came up overnight and perished overnight.
God boils it down for Jonah: here is something that you contributed nothing for, you only owned for one day, you didn't even tend to it, and yet you mourn over it like it was your only child.
4:11 - Should I not have compassion on Nineveh, the great city in which there are more than 120,000 persons who do not know the difference between their right and left hand, as well as many animals?”
With a final question, God shows what compassion truly is: concern for a whole city full of people, and depending on how you interpret it, 120,000 children! God then tacks on the animals as if to separate two "innocent" groups that would have been destroyed along with the city of wicked Gentiles.
God drives home the point that Jonah didn't care one bit for a city of over 600,000 people, 120,000 of which were children. Jonah didn't even care for the animals that would have been destroyed.
The writer intentionally, I think, leaves the question unanswered. It is to be answered by the reader. The original audience would have read this as a harsh rebuke of their attitude which was just like Jonah's.
God wraps up His message with a scathing rebuke of the prophet and by association, the nation of Israel.
Jonah cared only for himself and his comfort while God is concerned about turning people to Himself in salvation. Jonah sees the loss of life as justice while God sees the sparing of Nineveh as a demonstration of His mercy.
Chapter 4 Notes and Summary
Chapter 4 serves to show that God is not only concerned about obedience; He desires obedience from a pure heart. Outward motivation can achieve the work that God engages (the salvation of Nineveh), but God also wants to achieve the work that He engages in men as well (sanctification).
Chapter 4 boiled down to a sentence: God is compassionate; Jonah is not.