Abu Hurayrah said, "I never saw Hasan without my eyes filling with tears. That is because one day the Prophet ﷺ went out and found me in the mosque. He took my hand, and I walked along with him. He did not speak to me until we reached the market of Banu Qaynuqa. He walked through it, looked around, then turned back, and I was with him until we came to the mosque. He sat down and gathered his garment around him, then said, 'Where is the little one? Call the little one to me.'Hasan came running and threw himself into his lap. Then he placed his hand into his beard, and the Prophet ﷺ began to open his mouth, placing his mouth into his. Then he said, 'O Allah, I love him, so love him, and love whoever loves him.'"
ما رأيت حسنا قط إلا فاضت عيناي دموعا، وذلك أن النبي ﷺ يخرج يوما فوجدني في المسجد فأخذ بيدي، فانطلقت معه، فما كلمني حتى جئنا سوق بني قينقاع، فطاف فيه ونظر، ثم انصرف وأنا معه حتى جئنا المسجد، فجلس فاحتسبي ثم قال: أين لكاع؟ ادع لي لكاع، فجاء حسن يشتد فوقع في حجره، ثم أدخل يده في لحيته، ثم جعل النبي ﷺ يفتح فاه، فيدخل فاه في فيه، ثم قال: اللهم إني أحبه فأحبه وأحب من يحبه.
Ahmad (10891), Bukhari in Adab al-Mufrad (1183), and Abu Naeem in Hilyah (2/35) all narrated it through Hisham bin Saad, from Naeem bin Abdullah Mujmir, from Abu Hurairah, who said, and then he related it.Its chain of transmission is hasan because of Hisham bin Saad Madani, for there is disagreement about him, though his hadith is hasan when he does not contradict others. The story itself is sahih and firmly established, having been reported by the two Shaykhs (Bukhari and Muslim) in their two Sahihs through another route from Abu Hurairah, though without mention of sitting with the knees drawn up. And Allah knows best what is correct.