I saw the Messenger of Allah ﷺ on the pulpit with Hasan beside him. He would turn toward the people once and toward him once, saying, "This son of mine is a leader, and perhaps Allah will reconcile through him two great factions of the Muslims."
أخبرنا محمد بن منصور قال حدثنا سفيان قال حدثنا أبو موسى إسرائيل بن موسى قال سمعت الحسن يقول سمعت
لقد رأيت رسول الله ﷺ على المنبر والحسن معه وهو يقبل على الناس مرة وعليه مرة ويقول إن ابني هذا سيد ولعل الله أن يصلح به بين فئتين من المسلمين عظيمتين
Bukhari narrated it in the Book of Reconciliation, in the chapter on the saying of the Prophet ﷺ to Hasan bin Ali , "Indeed...," hadith no. 2704, from the hadith of Sufyan bin Uyayna with the same wording. It is also found in al-Kubra, hadith no. 1718. This is a leader