From Sahih Bukhari (Hadith 5635):
Narrated Al-Bara' bin `Azib:Allah's Messenger (ﷺ) ordered us to do seven things and forbade us from seven. He ordered us to visit the sick, to follow funeral processions, (to say) to a sneezer, (May Allah bestow His Mercy on you, if he says, Praise be to Allah), to accept invitations, to greet (everybody), to help the oppressed and to help others to fulfill their oaths. He forbade us to wear gold rings, to drink in silver (utensils), to use Mayathir (silken carpets placed on saddles), to wear Al-Qissi (a kind of silken cloth), to wear silk, Dibaj or Istabraq (two kinds of silk)
Reference: Bukhari 5635