Sahih Muslim Book 31, Hadith Number 5952.

Abu Huraira reported: I went along with Allah’s Messenger (may peace be upon him) at a time during the day but he did not talk to me and I did not talk to him until he reached Bazar of Banfi Qainuqal. He came back to the tent of Fatima and said: Is the little chap (meaning Hasan) there? We were under the impression that his mother had detained him in order to bathe him and dress him and garland him with a sweet garland. Not much time had passed that he (Hasan) came running until both of them embraced each other, thereupon Allah’s Messenger (may peace be upon him) said: O Allah, I love him; love him Thou and love one who loves him (Hasan).