ENOfficial
He said, pointing to the little finger of his left hand, “The Prophet’s signet-ring was on this.” Muslim transmitted it.
Source: sunnah.com
Other translations
Arabic
وَعَنْهُ قَالَ: كَانَ خَاتَمُ النَّبِيِّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ فِي هَذِهِ وَأَشَارَ إِلَى الْخِنْصِرِ منْ يَده الْيُسْرَى. رَوَاهُ مُسلم
sunnah.com