It is narrated from Zaid Ibn Abi Wahab that one day Amir’ul-Mu’minin (a.s) came out of his house in such a way that his lower garment was having patches all over it. Ibn Na’ja the Khariji, became angry on seeing him and said, “You are the Chief of the believers, such clothes do not befit you.” Imam (a.s) replied, “What concern do you have with my clothes. This dress of mine is remote from pride and it is deserving to serve as a model for Muslims.”
Ahmad Ibn Hanbal has written in Manaqib that during the temporal rule of Amir’ul-Mu’minin (a.s) he purchased a shirt worth three dirhams. Its sleeves were somewhat long, which he got shortened. Then he said, “Thanks be to God Who bestowed such a dress.” One day he was standing in the Kufa market to sell his sword, and he kept repeating, “By Allah, if I had the money to purchase this garment, I would not have sold my sword.”
Reference :Akhlaq al-A’imma, Morals & Manners of the Holy Imams