Messenger of Allah ﷺ wanted to write a letter to a group of people or some non-Arabs. It was said to him, "They do not accept any letter unless it is stamped." So the Prophet ﷺ had a silver ring made for himself, and on it was engraved: 'Muhammad, the Messenger of Allah'. .. as if I am now looking at the glitter of the ring on the finger (or in the palm) of the Prophet ﷺ .  

أَنَّ نَبِيَّ اللَّهِ ﷺ أَرَادَ أَنْ يَكْتُبَ إِلَى رَهْطٍ أَوْ أُنَاسٍ مِنَ الأَعَاجِمِ فَقِيلَ لَهُ إِنَّهُمْ لاَ يَقْبَلُونَ كِتَابًا إِلاَّ عَلَيْهِ خَاتَمٌ فَاتَّخَذَ النَّبِيُّ ﷺ خَاتَمًا مِنْ فِضَّةٍ نَقْشُهُ مُحَمَّدٌ رَسُولُ اللَّهِ فَكَأَنِّي بِوَبِيصِ أَوْ بِبَصِيصِ الْخَاتَمِ فِي إِصْبَعِ النَّبِيِّ ﷺ أَوْ فِي كَفِّهِ  

Messenger of Allah ﷺ had a silver ring made for himself and it was worn by him on his hand. Afterwards it was worn by Abu Bakr, and then by ʿUmar, and then by ʿUthman till it fell in the Aris well. (On that ring) was engraved: 'Muhammad, the Messenger of Allah."  

اتَّخَذَ رَسُولُ اللَّهِ ﷺ خَاتَمًا مِنْ وَرِقٍ وَكَانَ فِي يَدِهِ ثُمَّ كَانَ بَعْدُ فِي يَدِ أَبِي بَكْرٍ ثُمَّ كَانَ بَعْدُ فِي يَدِ عُمَرَ ثُمَّ كَانَ بَعْدُ فِي يَدِ عُثْمَانَ حَتَّى وَقَعَ بَعْدُ فِي بِئْرِ أَرِيسَ نَقْشُهُ مُحَمَّدٌ رَسُولُ اللَّهِ