That he heard Allah's Messenger (ﷺ) saying, "A slave of Allah may utter a word without thinking whether it is right or wrong, he may slip down in the Fire as far away a distance equal to that between the east."
Sahih al-Bukhari Book 81, Hadith 66
← Previous Hadith My ears heard and my heart grasped (the statement which) the Prophet (ﷺ) said, "The period for keeping one's guest is three days (and don't forget) his reward." It was asked, "What is his reward?" He said, "In the first night and the day he should be given a high class quality of meals; and whoever believes in Allah and the Last Day, should entertain his guest generously; and whoever believes in Allah and the Last Day should talk what is good (sense) or keep quiet."

Sahih al-Bukhari Book 81, Hadith 65 Next Hadith → The Prophet; said, "A slave (of Allah) may utter a word which pleases Allah without giving it much importance, and because of that Allah will raise him to degrees (of reward): a slave (of Allah) may utter a word (carelessly) which displeases Allah without thinking of its gravity and because of that he will be thrown into the Hell-Fire."

Sahih al-Bukhari Book 81, Hadith 67