The Messenger of Allah ﷺ said, "A man may speak a word, seeing no harm in it, that will plunge him seventy autumns down into the Fire."
حدثنا ابن أبي عدي عن محمد بن إسحاق حدثني محمد بن إبراهيم عن عيسى بن طلحة
قال رسول الله ﷺ إن الرجل ليتكلم بالكلمة لا يرى بها بأسا يهوي بها سبعين خريفا في النار
Its isnad is sahih. Muhammad bin Ibrahim is Taymi. Isa is Ibn Talha bin Ubaydullah Taymi. The hadith will come again at 7945 with this same isnad, and will also come at 8643 through the narration of Hasan from Abu Hurairah. Tirmidhi related it in 2:260 from Muhammad bin Bashshar from Ibn Abu Adi, with this isnad. He said, this is a hasan hadith, gharib from this angle. His commentator said, Ibn Majah and Hakim also related it. Its meaning is established in the Sahihayn and elsewhere, through other routes. See what comes at 8392, and Bukhari 11:265-267, and Muslim 2:290, and Targheeb wal-Tarheeb 4:9.As for his saying "seventy autumns," it means seventy years. Ibn Athir said, the autumn is the well-known season among the seasons of the year, the one between summer and winter.