'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.

“Is it a fast like this which I choose, a day for a man to humble himself?Is it for bowing one’s head like a reedAnd for spreading out sackcloth and ashes as a bed?Will you call this a fast, even an acceptable day to the Lord?

So I gave my attention to the Lord God to seek Him by prayer and supplications, with fasting, sackcloth and ashes.