The word of the Lord came to Jonah a second time, saying, “Get up, go to Nineveh, that great city, and proclaim to it the message that I tell you.” So Jonah set out and went to Nineveh, according to the word of the Lord. Now Nineveh was an exceedingly large city, a three days’ walk across. Jonah began to go into the city, going a day’s walk. And he cried out, “Forty days more, and Nineveh shall be overthrown!” And the people of Nineveh believed God; they proclaimed a fast, and everyone, great and small, put on sackcloth.
When God saw what they did, how they turned from their evil ways, God changed his mind about the calamity that he had said he would bring upon them; and he did not do it.
-Jonah 3: 1-5, 10