Sunan an-Nasa'i, Hadith 5205 ⓘ
Iyas bin Al-Harith bin Al-Mu'aiqib narrated that his grandfather Mu'aiqib said: "The ring of the Prophet [SAW] was made of iron with silver twisted around it." He said: "And sometimes it was on my hand." And Mu'aiqib was the keeper of the ring of the Messenger of Allah [SAW].
أَخْبَرَنَا عَمْرُو بْنُ عَلِيٍّ، عَنْ أَبِي عَتَّابٍ، سَهْلِ بْنِ حَمَّادٍ ح وَأَنْبَأَنَا أَبُو دَاوُدَ، قَالَ { حَدَّثَنَا سَهْلُ بْنُ حَمَّادٍ، قَالَ } حَدَّثَنَا أَبُو مَكِينٍ، قَالَ حَدَّثَنَا إِيَاسُ بْنُ الْحَارِثِ بْنِ الْمُعَيْقِيبِ، عَنْ جَدِّهِ، مُعَيْقِيبٍ أَنَّهُ قَالَ كَانَ خَاتَمُ النَّبِيِّ صلى الله عليه وسلم حَدِيدًا مَلْوِيًّا عَلَيْهِ فِضَّةٌ - قَالَ - وَرُبَّمَا كَانَ فِي يَدِي . فَكَانَ مُعَيْقِيبٌ عَلَى خَاتَمِ رَسُولِ اللَّهِ صلى الله عليه وسلم .
also referenced under: Book 48, Hadith 166 (In-Book) & Volume 6, Book 48, Hadith 5208 (DarusSalam)