Jami` at-Tirmidhi, Hadith 1743 ⓘ
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 .
also referenced under: Book 24, Hadith 24 (In-Book) & Volume 3, Book 22, Hadith 1743 (DarusSalam)