When the Prophet ﷺ intended to write to the Byzantines, it was said to him, "Those people do not read your letter unless it is stamped." So the Prophet ﷺ took a silver ring and got 'Muhammad, the Apostle of Allah' engraved on it .... as if I am now looking at its glitter in his hand. (Using translation from Bukhārī 5875)   

لَمَّا أَرَادَ رَسُولُ اللهِ ﷺ أَنْ يَكْتُبَ إِلَى الرُّومِ قِيلَ لَهُ إِنَّهُمْ لَنْ يَقْرَءُوا كِتَابَكَ إِذَا لَمْ يَكُنْ مَخْتُومًا فَاتَّخَذَ خَاتَمًا مِنْ فِضَّةٍ وَنَقَشَهُ مُحَمَّدٌ رَسُولُ اللهِ قَالَ أَنَسٌ فَكَأَنَّمَا أَنْظُرُ إِلَى بَيَاضِهِ فِي يَدِهِ  

"The Messenger of Allah ﷺ had a ring made from silver, so he had 'Muhammad, the Messenger of Allah' engraved on it. Then he said: 'Do not engrave with it.' (Using translation from Tirmidhī 1745)   

أَنَّ النَّبِيَّ ﷺ صَنَعَ خَاتَمًا مِنْ وَرِقٍ فَنَقَشَ فِيهِ مُحَمَّدٌ رَسُولُ اللهِ ﷺ وَقَالَ لَا تَنْقُشُوا عَلَيْهِ  

Messenger of Allah ﷺ took a silver ring and had 'Muhammad, the Apostle' of Allah' engraved on it. The Prophet then said (to us), 'I have a silver ring with 'Muhammad, the Messenger of Allah engraved on it, so none of you should have the same engraving on his ring." (Using translation from Bukhārī 5877)   

أَنَّ رَسُولَ اللهِ ﷺ اتَّخَذَ خَاتَمًا مِنْ فِضَّةٍ وَنَقَشَ فِيهِ مُحَمَّدٌ رَسُولُ اللهِ وَقَالَ إِنِّي اتَّخَذْتُ خَاتَمًا مِنْ فِضَّةٍ وَنَقَشْتُ فِيهِ مُحَمَّدٌ رَسُولُ اللهِ فَلَا يَنْقُشْ أَحَدٌ عَلَى نَقْشِهِ