'Sackcloth and Ashes' in the Bible

When Mordecai learned all that had been done, he tore his clothes, put on sackcloth and ashes, and went out into the midst of the city and wailed loudly and bitterly.

In each and every province where the command and decree of the king came, there was great mourning among the Jews, with fasting, weeping and wailing; and many lay on sackcloth and ashes.