Sackcloth cloth made of black goats' hair, coarse, rough, and thick, used for sacks, and also worn by mourners (Genesis 37:34; Genesis 1:42; 2 Samuel 3:31; Esther 4:1, Esther 1:4; Psalms 30:11, etc.), and as a sign of repentance (Matthew 11:21). It was put upon animals by the people of Nineveh (Jonah 3:8).