(6) باب التَّكَلُّمِ بِالْكَلِمَةِ يَهْوِي بِهَا فِي النَّارِ
Abu Huraira reported Allah's Messenger (ﷺ) as saying:
The servant speaks words that he does not understand its repercussions but he sinks down in Hell-Fire farther than the distance between the east and the west.
Reference: Sahih Muslim 2988 b
In-book reference: Book 55, Hadith 65
USC-MSA web (English) reference(deprecated numbering scheme): Book 42, Hadith 7121