Musnad Ahmad 1034:118

'Affan narrated to us, Mahdi narrated to us, Wasil al-Ahdab narrated to us, from Abu Wa'il, from Hudhayfah, that it reached him that a man was spreading gossip (namim), so he said: I heard the Messenger of Allah, peace and blessings of Allah be upon him, say: "The gossip-monger (nammam) shall not enter Paradise."