I heard the Prophet ﷺ talking at the pulpit while Al-Hasan was sitting beside him, and he (i.e. the Prophet ) was once looking at the people and at another time Al-Hasan, and saying, "This son of mine is a Saiyid (i.e. chief) and perhaps Allah will bring about an agreement between two sects of the Muslims through him."  

سَمِعْتُ النَّبِيَّ ﷺ عَلَى الْمِنْبَرِ وَالْحَسَنُ إِلَى جَنْبِهِ يَنْظُرُ إِلَى النَّاسِ مَرَّةً وَإِلَيْهِ مَرَّةً وَيَقُولُ ابْنِي هَذَا سَيِّدٌ وَلَعَلَّ اللَّهَ أَنْ يُصْلِحَ بِهِ بَيْنَ فِئَتَيْنِ مِنَ الْمُسْلِمِينَ  

When Al-Hasan bin ʿAli moved with army units against Muawiya, ʿAmr bin AL-As said to Muawiya, "I see an army that will not retreat unless and until the opposing army retreats." Muawiya said, "(If the Muslims are killed) who will look after their children?" ʿAmr bin Al-As said: I (will look after them). On that, ʿAbdullah bin 'Amir and ʿAbdur-Rahman bin Samura said, "Let us meet Muawaiya and suggest peace." Al-Hasan Al-Basri added: No doubt, I heard that Abu Bakra said, "Once while the Prophet was addressing (the people), Al-Hasan (bin ʿAli) came and the Prophet ﷺ said, 'This son of mine is a chief, and Allah may make peace between two groups of Muslims through him."  

بَيْنَا النَّبِيُّ ﷺ يَخْطُبُ جَاءَ الْحَسَنُ فَقَالَ النَّبِيُّ ﷺ ابْنِي هَذَا سَيِّدٌ وَلَعَلَّ اللَّهَ أَنْ يُصْلِحَ بِهِ بَيْنَ فِئَتَيْنِ مِنَ الْمُسْلِمِينَ  

"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.'" (Using translation from Nasāʾī 1410)   

عَنْ أَبِي بَكَرَةَ رَأَيْتُ رَسُولَ اللهِ ﷺ عَلَى الْمِنْبَرِ وَحَسَنٌ مَعَهُ وَهُوَ يُقْبِلُ عَلَى النَّاسِ مَرَّةً وَعَلَيْهِ مَرَّةً وَيَقُولُ إِنَّ ابْنِي هَذَا سَيِّدٌ وَلَعَلَّ اللهَ أَنْ يُصْلِحَبِهِ بَيْنَ فِئَتَيْنِ مِنَ الْمُسْلِمِينَ  

The Messenger of Allah ﷺ said to al-Hasan ibn Ali. This son of mine is a Sayyid (chief), and I hope Allah may reconcile two parties of my community by means of him. Hammad's version has: And perhaps Allah may reconcile two large parties of Muslims by means of him. (Using translation from Abū Dāʾūd 4662)   

قَالَ رَسُولُ اللَّهِ ﷺ لِلْحَسَنِ بْنِ عَلِيٍّ «إِنَّ ابْنِي هَذَا سَيِّدٌ وَلَعَلَّ اللَّهَ أَنْ يُصْلِحَ بِهِ بَيْنَ فِئَتَيْنِ مِنَ الْمُسْلِمِينَ عَظِيمَتَيْنِ»  

[Machine] While the Prophet ﷺ was delivering a sermon, Hassan ibn Ali approached him and the Prophet ﷺ embraced him and said, "Indeed, my son here is a master and perhaps Allah (God) will bring about reconciliation through him between two factions of the Muslims."  

بَيْنَا النَّبِيُّ ﷺ يَخْطُبُ إِذْ صَعِدَ إِلَيْهِ الْحَسَنُ بْنُ عَلِيٍّ ؓ فَضَمَّهُ النَّبِيُّ ﷺ فَقَالَ «إِنَّ ابْنِي هَذَا سَيِّدٌ وَلَعَلَّ اللهَ ﷻ أَنْ يُصْلِحَ بِهِ بَيْنَ فِئَتَيْنِ مِنَ الْمُسْلِمِينَ»  

"عَنِ الحَسَنِ قَالَ: رَفَعَ رَسُولُ اللَّهِ ﷺ الْحَسَنَ بْنَ عَلَىٍّ مَعَهُ عَلَى الْمِنْبرِ، فَقَالَ: إن ابْنِى هَذَا سَيِّدٌ وَلَعَلَّ اللَّهَ -تَعَالَى- أَنْ يُصْلِحَ بِهِ بَيْنَ فِئَتَيْنِ مِنَ الْمُسْلِمِينَ".