Yahya bin Bukayr (may Allah have mercy on him) said: "Sayyiduna Hasan bin Ali bin Abi Talib (may Allah be pleased with him) passed away in the year 49 AH, and Sa'id bin al-As led his funeral prayer. His death took place in Madinah, and his age was forty-six or forty-seven."
Hadith Referenceالمعجم الكبير للطبراني / باب الحاء / 2683