He used to wear simple clothes and did not approve of wearing highly expensive clothes. He used to select his way of dressing himself.
He further sates in his renowned book Kashf al-Mahjub that Others, again, do not trouble themselves about clothes at all. They wear either a religious habit (aba) or an ordinary coat (qaba), whichever God may have given them; and if he keeps them naked, they remain in that state. I, who am Ali b. Uthman al-Jullabi, approve of this doctrine.
Source Kashf al-Mahjub, translated into English by Prof. Nicholson, Page 52, Published by Darul Ishaat, Pakistan