SHAFAQNA – The Grand Ayatollah Shobairi Zanjani answered a question about rubbing mud on clothes and walking barefoot for Muharram mourning ceremonies.
Question: Some mourners on the Day of Ashura rub mud on their clothes, and take off their shoes. What is the ruling about these acts?
The Grand Ayatollah Shobairi: There is no problem; rather, these are signs/examples of revering religious rituals, and it is Mostahab (religiously appropriate to carry them out).
Source: PERSIAN SHAFAQNA