Jonah 3:3-5 (NIV)
3 Jonah obeyed the word of the Lord and went to Nineveh. Now Nineveh was a very large city; it took three days to go through it. 4 Jonah began by going a day’s journey into the city, proclaiming, “Forty more days and Nineveh will be overthrown.” 5 The Ninevites believed God. A fast was proclaimed, and all of them, from the greatest to the least, put on sackcloth.