Abu Uthman says that we were in Azerbaijan when a letter from Sayyiduna Umar (may Allah be pleased with him) arrived, in which it was written: O Utbah bin Farqad! Guard yourself against luxury, wearing silk garments, and adopting the ways of the polytheists, because the Messenger of Allah (peace and blessings be upon him) forbade us from wearing silk garments except for a small amount, and the Prophet (peace and blessings be upon him) indicated this by raising his finger.