Jonah 3:4 TLB

[4] But the very first day when Jonah entered the city and began to preach, the people repented. Jonah shouted to the crowds that gathered around him, "Forty days from now Nineveh will be destroyed!" And they believed him and declared a fast; from the king on down, everyone put on sackcloth-the rough, coarse garments worn at times of mourning.