Riyad Us-Saliheen (Gardens of the Righteous)

Chapter 120
Excellence of giving up Elegant Clothes for Humility

802. Mu`adh bin Anas (May Allah be pleased with him) reported: Messenger of Allah (PBUH) said, "Whoever gives up wearing elegant and expensive garments out of humbleness, when he can do so, Allah will call him on the Day of Resurrection and before all the creations, He will give him the choice to wear whichever garment of Iman he would like to wear.''
[At-Tirmidhi].

Commentary: To adopt humility and not to assert superiority over others, according to this Hadith, is an excellent act with Allah. `The clothes of Iman' imply those special clothings of Jannah that Allah has prepared for sincere believers only.