Muhammad ibn Ishaq said:

I saw as-Salt ibn Abdullah ibn Nawfal ibn AbdulMuttalib wearing the signet-ring on his right small finger. I asked: What is this? He replied: I saw Ibn Abbas wearing his ring in this manner. He put its stone towards the upper part of his palm. Ibn Abbas also mentioned that the Messenger of Allah (ﷺ) used to wear his signet-ring in his manner.

حَدَّثَنَا عَبْدُ اللَّهِ بْنُ سَعِيدٍ، حَدَّثَنَا يُونُسُ بْنُ بُكَيْرٍ، عَنْ مُحَمَّدِ بْنِ إِسْحَاقَ، قَالَ رَأَيْتُ عَلَى الصَّلْتِ بْنِ عَبْدِ اللَّهِ بْنِ نَوْفَلِ بْنِ عَبْدِ الْمُطَّلِبِ خَاتَمًا فِي خِنْصَرِهِ الْيُمْنَى فَقُلْتُ مَا هَذَا قَالَ رَأَيْتُ ابْنَ عَبَّاسٍ يَلْبَسُ خَاتَمَهُ هَكَذَا وَجَعَلَ فَصَّهُ عَلَى ظَهْرِهَا ‏.‏ قَالَ وَلاَ يَخَالُ ابْنَ عَبَّاسٍ إِلاَّ قَدْ كَانَ يَذْكُرُ أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم كَانَ يَلْبَسُ خَاتَمَهُ كَذَلِكَ ‏.‏