Al-Hasan and others narrate: The first person to accept Islam was Sayyiduna Ali bin Abi Talib (may Allah be pleased with him), and at that time he was fifteen, or perhaps sixteen, years old.
Al-Tabarani recorded it, and its narrators are the narrators of the Sahih.
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب المناقب / 14603
Hadith Gradingمحدثین:إسنادہ صحیح
Hadith Takhrij«اخرجه الطبراني فى المعجم الكبير (163)»