He heard the Messenger of Allah ﷺ say, "A servant may utter a word that causes him to slip into the Fire a distance greater than that between the east and the west."
حدثنا قتيبة بن سعيد حدثنا بكر بن مضر عن يزيد بن الهاد عن محمد بن إبراهيم عن أبي سلمة
أنه سمع رسول الله ﷺ يقول إن العبد يتكلم بالكلمة يزل بها في النار أبعد ما بين المشرق والمغرب
Its isnad is sahih, it occurred previously at 8392 with similar wording, and it appears in Muslim 4/2290 in the Book of Zuhd, on the chapter of the man who speaks a word, and with wording close to it in Bukhari 8/125 in the Book of Riqaq, on the chapter of guarding the tongue.