It is related that Abu Hurayra said, "I never sae al-Hasan without my eyes overflowing with tears. That is because the Prophet, may Allah bless him and grant him peace, went out one day and I found him in the mosque. He took my hand and I went along with him. He did not speak to me until we reached the market of Banu Qaynuqa'. He walked around it and looked. Then he left and I left with him until we reached the mosque. He sat down and wrapped himself in his garment. Then he said, 'Where is the little one? Call the little one to me.' Hasan came running and jumped into his lap. Then he put his hand in his beard. Then the Prophet, may Allah bless him and grant him peace, opened his mouth and put his tongue in his mouth. Then he said, O Allah, I love him, so love him and the one who loves him!'"

حَدَّثَنَا إِبْرَاهِيمُ بْنُ الْمُنْذِرِ قَالَ‏:‏ حَدَّثَنِي ابْنُ أَبِي فُدَيْكٍ قَالَ‏:‏ حَدَّثَنِي هِشَامُ بْنُ سَعْدٍ، عَنْ نُعَيْمِ بْنِ الْمُجْمِرِ، عَنْ أَبِي هُرَيْرَةَ قَالَ‏:‏ مَا رَأَيْتُ حَسَنًا قَطُّ إِلاَّ فَاضَتْ عَيْنَايَ دُمُوعًا، وَذَلِكَ أَنَّ النَّبِيَّ صلى الله عليه وسلم خَرَجَ يَوْمًا، فَوَجَدَنِي فِي الْمَسْجِدِ، فَأَخَذَ بِيَدِي، فَانْطَلَقْتُ مَعَهُ، فَمَا كَلَّمَنِي حَتَّى جِئْنَا سُوقَ بَنِي قَيْنُقَاعٍ، فَطَافَ فِيهِ وَنَظَرَ، ثُمَّ انْصَرَفَ وَأَنَا مَعَهُ، حَتَّى جِئْنَا الْمَسْجِدَ، فَجَلَسَ فَاحْتَبَى ثُمَّ قَالَ‏:‏ أَيْنَ لَكَاعٌ‏؟‏ ادْعُ لِي لَكَاعًا، فَجَاءَ حَسَنٌ يَشْتَدُّ فَوَقَعَ فِي حِجْرِهِ، ثُمَّ أَدْخَلَ يَدَهُ فِي لِحْيَتِهِ، ثُمَّ جَعَلَ النَّبِيُّ صلى الله عليه وسلم يَفْتَحُ فَاهُ فَيُدْخِلُ فَاهُ فِي فِيهِ، ثُمَّ قَالَ‏:‏ اللَّهُمَّ إِنِّي أُحِبُّهُ، فَأَحْبِبْهُ، وَأَحِبَّ مَنْ يُحِبُّهُ‏.‏
GradeHasan (Al-Albani)  حـسـن   (الألباني) حكم     :
English reference : Book 48, Hadith 1183
Arabic reference : Book 1, Hadith 1183