حَدَّثَنَا قُتَيْبَةُ بْنُ سَعِيدٍ، وَغَيْرُ وَاحِدٍ، عَنْ عَبْدِ اللهِ بْنِ وَهْبٍ، عَنْ يُونُسَ، عَنِ ابْنِ شِهَابٍ، عَنْ أَنَسِ بْنِ مَالِكٍ، قَالَ‏:‏ كَانَ خَاتَمُ النَّبِيِّ صلى الله عليه وسلم مِنْ وَرِقٍ، وَكَانَ فَصُّهُ حَبَشِيًّا‏.‏

Anas ibn Malik said

"The Prophet (Allah bless him and give him peace) wrote to Chosroes, Caesar and the Negus, whereupon he was told: 'The non-Arabs will not accept a letter unless it bears a seal.' Allah’s Messenger (Allah bless him and give him peace) therefore cast a signet which had a silver ring, and on which was engraved; “Muhammad is the Messenger of Allah.”