Musnad Abu Ya'la al-Mawsili 156:12

Narrated to us Shayban, narrated to us Jarir, from al-Hasan, from Abu Hurayrah, who said: The Messenger of Allah (may Allah bless him and grant him peace) said: "Indeed, a man speaks a word, and he does not perceive that it reaches where it reaches, [yet] he falls by it into the Fire for seventy autumns."