Abu Bakrah said: "I saw the Messenger of Allah (ﷺ) on the Minbar, and Al-Hasan was with him. He would turn to the people sometimes and turn to him (Al-Hasan) sometimes, and he said: 'This son of mine is a leader (Sayyid) and Allah may make peace between two large groups of Muslims through him.'"
Source: sunnah.com
Other translations
Arabic
أَخْبَرَنَا مُحَمَّدُ بْنُ مَنْصُورٍ، قَالَ حَدَّثَنَا سُفْيَانُ، قَالَ حَدَّثَنَا أَبُو مُوسَى، إِسْرَائِيلُ بْنُ مُوسَى قَالَ سَمِعْتُ الْحَسَنَ، يَقُولُ سَمِعْتُ أَبَا بَكْرَةَ، يَقُولُ لَقَدْ رَأَيْتُ رَسُولَ اللَّهِ صلى الله عليه وسلم عَلَى الْمِنْبَرِ وَالْحَسَنُ مَعَهُ وَهُوَ يُقْبِلُ عَلَى النَّاسِ مَرَّةً وَعَلَيْهِ مَرَّةً وَيَقُولُ " إِنَّ ابْنِي هَذَا سَيِّدٌ وَلَعَلَّ اللَّهَ أَنْ يُصْلِحَ بِهِ بَيْنَ فِئَتَيْنِ مِنَ الْمُسْلِمِينَ عَظِيمَتَيْنِ " .
sunnah.com