Sahih Bukhari Volume 007, Book 070, Hadith Number 553.
Narrated By Al-Bara bin Azib : Allah's Apostle ordered us to do seven things and forbade us to do seven other things. He forbade us to wear gold rings, silk, Dibaj, Istabriq, Qissy, and Maithara; and ordered us to accompany funeral processions, visit the sick and greet everybody. (See Hadith No. 104)