Musnad Abu Ya'la al-Mawsili 106:34

Ishaq narrated to us, Abu Mu'awiyah narrated to us, Qunan ibn Abdullah narrated to us, from Abd al-Rahman ibn Awsajah, from al-Bara', who said: The Messenger of Allah (peace be upon him) said: "Spread the greeting, and you will be safe. And *al-asharah* is evil." Abu Mu'awiyah said: Meaning, excessive playfulness.