Sahih Bukhari Volume 008, Book 074, Hadith Number 253A.
Narated By Al-Bara' bin 'Azib : Allah's Apostle ordered us to do seven (things): to visit the sick, to follow the funeral processions, to say Tashmit to a sneezer, to help the weak, to help the oppressed ones, to propagate As-Salam (greeting), and to help others to fulfill their oaths (if it is not sinful). He forbade us to drink from silver utensils, to wear gold rings, to ride on silken saddles, to wear silk clothes, Dibaj (thick silk cloth), Qassiy and Istabraq (two kinds of silk). (See Hadith No. 539, Vol. 7)