Musnad Ahmad 30:3694

'Abd al-Samad narrated to us, Hammad narrated to us, from Suhayl, from his father, from Abu Hurayrah, that the Messenger of Allah (peace and blessings of Allah be upon him) said: "No people sit in a gathering, then disperse without the remembrance of Allah, except that they disperse like the carcass of a donkey, and that gathering will be a source of regret for them on the Day of Resurrection."