Ash-Shama'il Al-Muhammadiyah, Book 12, Hadith 88 (In-Book)

Hazrat Ibn Umar radiallahu anhu says that Rasulullah sallallahu alayhe wasallam had a ring made of silver. He used it as a seal (Stamp) on letters etc., but did not wear it

حَدَّثَنَا قُتَيْبَةُ حَدَّثَنَا أَبُو عَوَانَةَ، عَنْ أَبِي بِشْرٍ، عَنْ نَافِعٍ، عَنِ ابْنِ عُمَرَ، أَنَّ النَّبِيَّ صلى الله عليه وسلم اتَّخَذَ خَاتَمًا مِنْ فِضَّةٍ، فَكَانَ يَخْتِمُ بِهِ وَلا يَلْبَسُهُ‏.‏

also referenced under: Book 11, Hadith 83 (English)