Hadith 2092
Anas b. Malik reported that when Allah's Messenger (may peace be upon him) decided to write letters to the Byzantine (Emperor) they (his Companions) told him that they would not read a letter unless it is sealed. (Then) Allah's Messenger (may peace be upon him) had a silver ring made (for himself), (its shape is so vivid in my mind) as if I see its brightness in the band of Allah's Messenger (may peace be upon him) and its engravement was (Muhammad, Messenger of Allah).
حَدَّثَنَا مُحَمَّدُ بْنُ الْمُثَنَّى، وَابْنُ، بَشَّارٍ قَالَ ابْنُ الْمُثَنَّى حَدَّثَنَا مُحَمَّدُ بْنُ جَعْفَرٍ، حَدَّثَنَا شُعْبَةُ، قَالَ سَمِعْتُ قَتَادَةَ، يُحَدِّثُ عَنْ أَنَسِ بْنِ مَالِكٍ، قَالَ لَمَّا أَرَادَ رَسُولُ اللَّهِ صلى الله عليه وسلم أَنْ يَكْتُبَ إِلَى الرُّومِ - قَالَ - قَالُوا إِنَّهُمْ لاَ يَقْرَءُونَ كِتَابًا إِلاَّ مَخْتُومًا . قَالَ فَاتَّخَذَ رَسُولُ اللَّهِ صلى الله عليه وسلم خَاتَمًا مِنْ فِضَّةٍ كَأَنِّي أَنْظُرُ إِلَى بَيَاضِهِ فِي يَدِ رَسُولِ اللَّهِ صلى الله عليه وسلم نَقْشُهُ مُحَمَّدٌ رَسُولُ اللَّهِ .