Why is repentance significant in the story of Jonah?

In the book of Jonah, repentance is a central theme that highlights God's mercy and grace towards sinners. Jonah was sent to Nineveh to call the people to repentance because their wickedness had reached its limit. Their subsequent repentance, prompted by Jonah’s reluctant message, showcases the heart of God—He desires to extend grace and forgiveness rather than judgment. This is poignantly illustrated in Matthew 12, where Jesus points out that the Ninevites repented at Jonah's preaching, contrasting their response with that of the Israelites who were witnessing Christ. Repentance signifies acknowledgment of sin and the turning away from it to be reconciled with God. It emphasizes that no one is beyond hope and that God patiently calls sinners back to Himself.