'Haircloth' in the Bible

In their streets they are covering themselves with haircloth: on the tops of their houses, and in their public places, there is crying and bitter weeping.

And on hearing it Hezekiah took off his robe and put on haircloth and went into the house of the Lord.

And he sent Eliakim, who was over the house, and Shebna the scribe, and the chief priests, dressed in haircloth, to Isaiah the prophet, the son of Amoz.

By me the heavens are clothed with black, and I make haircloth their robe.

Have I given orders for such a day as this? a day for keeping yourselves from pleasure? is it only a question of the bent head, of putting on haircloth, and being seated in the dust? is this what seems to you a holy day, well-pleasing to the Lord?