"The Ninevites believed God. They declared a fast, and all of them, from the greatest to the least, put on sackcloth." NIV translation
What an amazing verse we have here! Exactly what Jonah had feared is what happens in that the Ninevites believed God. This warrior people who were used to relying on themselves and their own strength believed in God and his coming judgment. Not only did they believe but they also took action as everyone humbled themselves (put on sackcloth). This can give us comfort in that we all probably know of someone that we want to come to Jesus but it seems that their heart is so hardened. Take heart as God can do with them just what He did with the entire city of Nineveh.
"When the news reached the king of Nineveh, he rose from his throne, took off his royal robes, covered himself with sackcloth and sat down in the dust." NIV translation
The greatest of these people (the king) repented at the hearing of the Word. What a picture this is of humility as it brings to mind Jesus leaving the throne in heaven to come and be born of a woman. The king of Nineveh did it hoping that God would spare his people but Jesus humbled Himself for our benefit. We were not His people and in fact we were His enemies.
"Then he issued a proclamation in Nineveh: 'By the decree of the king and his nobles: Do not let any man or beast, herd or flock, taste anything; do not let them eat or drink. But let man and beast be covered with sackcloth. Let everyone call urgently on God. Let them give up their evil ways and their violence. Who knows? God may yet relent and with compassion turn from his fierce anger so that we will not perish.'" NIV translation
Not only did the king repent but he issued a decree for all of Nineveh to do so as well. He instituted a very extreme fast as not only did he tell the people not to eat but he also told them not to have drink. He even went so far as to call for a fast for their animals. This great kingdom is doing some serious humbling of themselves. The king also told them to pray and to do so "urgently" as well as giving up their evil ways in hopes of God's mercy. This is a very true picture of repentance as it is not only a change of attitude but also a change of actions. We are called to this same repentance and God has even graciously given us the gift (Holy Spirit) to give us the power to change our actions. You can see this in Acts 2:38 where Peter issued the same call to radical repentance.
"When God saw what they did and how they turned from their evil ways, he had compassion and did not bring upon them the destruction he had threatened." NIV translation
What a picture of a merciful God in that He forgave the people of Nineveh when they repented. That same radical forgiveness is available for us as well. No matter how bad the things we have done seem, God will accept our repentance and spare us His wrath. Not only did God give Jonah a second chance in this chapter but He also gave the Ninevites another chance and they accepted. If you are looking for a second chance (or maybe a third, fourth, etc.) God is waiting!