There are issues of Clothing in Islam. Every single movement of traditional Islam How does the clergy in that movement dress. Frankly, they all dress according to the historical norms of a particular manifestation of Islam, in a particular Muslim majority land, in a particular century or era and for them this becomes religiosity. so you go to one version of traditionalists Islam and you should wear the white "Kurta shalwar" that say and if you don't wear it and I speak from experience you will not give the "Khutbah".In another version of traditionalist Islam, you have to wear the "thobe" And yet other versions are going to be the "Jellabiya" and the other fourth there's got to be should this and that.