'Sackcloth' in the Bible

And his servants said unto him, Behold now, we have heard that the kings of the house of Israel are merciful kings: let us, I pray thee, put sackcloth on our loins, and ropes upon our heads, and go out to the king of Israel: peradventure he will save thy life.

So they girded sackcloth on their loins, and put ropes on their heads, and came to the king of Israel, and said, Thy servant Benhadad saith, I pray thee, let me live. And he said, Is he yet alive? he is my brother.

And it came to pass, when Ahab heard those words, that he rent his clothes, and put sackcloth upon his flesh, and fasted, and lay in sackcloth, and went softly.