Musnad Ahmad 25:792

'Affan narrated to us, Abu 'Awanah narrated to us, he said: Abu Hamzah informed us, he said: I heard Ibn 'Abbas saying: I was a young boy running with the boys. He said: Then I turned around, and behold, the Prophet of Allah (ﷺ) was behind me, approaching. I said: The Prophet of Allah (ﷺ) has not come except for me. He said: So I ran to hide behind the door of a house. He said: I did not realize until he reached me. He said: He took hold of the back of my neck and gave me a light slap. He said: "Go and call Mu'awiyah for me," and he was his scribe. He said: So I ran and said: Answer the Prophet of Allah (ﷺ), for he has a need.