'Sackcloth and Ashes' in the Bible

When Mordecai learned all that had occurred, he tore his clothes, put on sackcloth and ashes, went into the middle of the city, and cried loudly and bitterly.

There was great mourning among the Jewish people in every province where the king’s command and edict came. They fasted, wept, and lamented, and many lay on sackcloth and ashes.