Hadith
أَخْبَرَنَا الْعَبَّاسُ بْنُ عَبْدِ الْعَظِيمِ الْعَنْبَرِيُّ، قَالَ حَدَّثَنَا عُثْمَانُ بْنُ عُمَرَ، قَالَ حَدَّثَنَا يُونُسُ، عَنِ الزُّهْرِيِّ، عَنْ أَنَسٍ، أَنَّ النَّبِيَّ صلى الله عليه وسلم اتَّخَذَ خَاتَمًا مِنْ وَرِقٍ فَصُّهُ حَبَشِيٌّ وَنُقِشَ فِيهِ مُحَمَّدٌ رَسُولُ اللَّهِ .
It was narrated from Anas that :The Prophet [SAW] wore a ring of silver with an Ethiopian stone (Fass), on which was inscribed (the phrase): "Muhammad Rasul Allah (Muhammad the Messenger of Allah)
Sahih · Abu Ghuddah
Sunan an-Nasa'i 5196 ·Book 48, Hadith 157·Also available on sunnah.com·