To wear the ring on the little finger Sahih al-Bukhari 5874
Arabic hadith text
حَدَّثَنَا أَبُو مَعْمَرٍ، حَدَّثَنَا عَبْدُ الْوَارِثِ، حَدَّثَنَا عَبْدُ الْعَزِيزِ بْنُ صُهَيْبٍ، عَنْ أَنَسٍ ـ رضى الله عنه ـ قَالَ صَنَعَ النَّبِيُّ صلى الله عليه وسلم خَاتَمًا قَالَ "إِنَّا اتَّخَذْنَا خَاتَمًا، وَنَقَشْنَا فِيهِ نَقْشًا، فَلاَ يَنْقُشْ عَلَيْهِ أَحَدٌ ". قَالَ فَإِنِّي لأَرَى بَرِيقَهُ فِي خِنْصَرِهِ
Translation
Narrated Anas
The Prophet (ﷺ) got a ring made for himself and said, "I have got a ring made (for myself) and engraved a certain engraving on it so none of you should get such an engraving on his ring." I saw the glitter of the ring on his little finger.