Musnad Ahmad 1034:65

Yahya ibn Sa'id al-Qattan Abu Sa'id al-Ahwal narrated to us, from al-A'mash, Ibrahim narrated to me about sixty years ago, from Hammam ibn al-Harith, who said: A man passed by Hudhayfah, and it was said: "This man carries speech (gossip) to the commanders." He said: I heard the Messenger of Allah, may Allah bless him and grant him peace, say—or he said: The Messenger of Allah, may Allah bless him and grant him peace, said: "A qattat (gossip/slanderer) will not enter Paradise."