1. The people of Nineveh believed in God and repented of their sins.
“Repentance is a change of mind issuing in a changed life.” —J.I. Packer
“If Jonah’s reemergence from the great fish spurred the Ninevites to a hopeful repentance, how much more ought we to be persuaded by the resurrection of Jesus Christ.” —Richard Phillips
2. God didn’t destroy the people of Nineveh because they repented of their sins.
“When God announces that his judgment is about to fall upon the sinful, it is a statement of what will inevitably happen if they continue on their present course. But it is a conditional statement. It is intended to alert the wayward and bring them to repentance. If that occurs, then God responds appropriately to the changed circumstances. … Though it may not be explicitly stated, the announcement of impending disaster is conditioned on continuing disobedience, just as enjoyment of the blessings of God’s covenant is conditioned on obedience.” —John MacKay