σάκκῳ  [2 verses](noun sg masc dat) "Sackcloth" is sakkos, which is "a coarse cloth of hair" used for sacks because it was uncomfortable for clothing. This was worn by people as a signing of mourning or penance.  - "Sackcloth" is "a coarse cloth of hair" used for sacks because it was uncomfortable for clothing. This was worn by people as a signing of mourning or penance. This is not a common term for Christ to use.