Musnad Ahmad 658:172

Yahya ibn Adam narrated to us, Sufyan narrated to us, from Ash'ath ibn Abi al-Sha'tha', from Mu'awiyah ibn Suwayd ibn Muqarrin, from al-Bara' ibn 'Azib, who said: "The Messenger of Allah (peace and blessings of Allah be upon him) commanded us with seven and forbade us from seven. He commanded us: to visit the sick, to follow the funeral processions, to answer the caller, to spread the greeting of peace, to say 'yarhamuk Allah' (may Allah have mercy on you) to the sneezer, to fulfill the oath, and to aid the oppressed. And he forbade us from: gold rings, silver vessels, silk, dibaj (thick silk), istabraq (brocade), red saddle-cloths, and al-qassi (a type of silk-blend fabric)."