The Messenger of Allah ﷺ said, "A servant may utter a word without giving it any thought, and because of it he plunges into the Fire a distance greater than that between the east and the west."
أن رسول الله ﷺ قال: إن العبد ليتكلم بالكلمة ما يتبين فيها، يهوي بها في النار أبعد ما بين المشرق والمغرب.
Bukhari narrated it in the Book of Raqaiq (647), and Muslim in the Book of Zuhd and Raqaiq (2988: 50), both through Yazid bin Had, from Muhammad bin Ibrahim, from Isa bin Talha, from Abu Hurairah, who mentioned it.