Musnad Ahmad 509:13

'Affan narrated to us, Wuhayb narrated to us, 'Abdullah ibn 'Uthman ibn Khuthaym narrated to us, from Sa'id ibn Abi Rashid, from Ya'la al-'Amiri, that he went out with the Messenger of Allah (may Allah bless him and grant him peace) to a meal to which he had been invited. He said: The Messenger of Allah (may Allah bless him and grant him peace) went ahead of the people, and Husayn was playing with some boys. The Messenger of Allah (may Allah bless him and grant him peace) wanted to take him. He said: The child began to run here once and there once, and the Messenger of Allah (may Allah bless him and grant him peace) kept making him laugh until he caught him. He said: He placed one of his hands under the back of his neck and the other under his chin, then he placed his mouth upon his mouth and kissed him, and said: "Husayn is from me and I am from Husayn. May Allah love whoever loves Husayn. Husayn is a grandson among the grandsons."