Sunan an-Nasa'i, Hadith 5284 ⓘ
It was narrated that Anas said: "It is as if I can see the whiteness of the Prophet's ring on his left finger."
أَخْبَرَنَا الْحُسَيْنُ بْنُ عِيسَى الْبِسْطَامِيُّ، قَالَ حَدَّثَنَا سَلْمُ بْنُ قُتَيْبَةَ، عَنْ شُعْبَةَ، عَنْ قَتَادَةَ، عَنْ أَنَسٍ، قَالَ كَأَنِّي أَنْظُرُ إِلَى بَيَاضِ خَاتَمِ النَّبِيِّ صلى الله عليه وسلم فِي إِصْبَعِهِ الْيُسْرَى .
also referenced under: Book 48, Hadith 245 (In-Book) & Volume 6, Book 48, Hadith 5286 (DarusSalam)