The Prophet [SAW] had a ring and he said: "We have had a ring made with an inscription, and no one else should copy this inscription." It is as if I can see its shining on the little finer of the Messenger of Allah [SAW]. (Using translation from Nasāʾī 5282)
أَنَّ النَّبِيَّ ﷺ اصْطَنَعَ خَاتَمًا فَقَالَ «إِنَّا قَدِ اتَّخَذْنَا خَاتَمًا وَنَقَشْنَا عَلَيْهِ نَقْشًا فَلَا يَنْقُشْ عَلَيْهِ أَحَدٌ فإِنِّي لَأَرَى بَرِيقَهُ فِي خِنْصَرِ رَسُولِ اللهِ ﷺ»