Narrated by:Narrated Ja'far bin Muhammad :
Narrated from his father who said: "Al-Hasan and Al-Husain wore their ring on their left hand." This Hadith is Hasan Sahih.
حَدَّثَنَا قُتَيْبَةُ، حَدَّثَنَا حَاتِمُ بْنُ إِسْمَاعِيلَ، عَنْ جَعْفَرِ بْنِ مُحَمَّدٍ، عَنْ أَبِيهِ، قَالَ كَانَ الْحَسَنُ وَالْحُسَيْنُ يَتَخَتَّمَانِ فِي يَسَارِهِمَا . وَهَذَا حَدِيثٌ حَسَنٌ صَحِيحٌ .
Tirmizi
The Book on Clothing • Hadith 1794