Abu 'Abdur-Rahman Bilal bin Al-Harith Al-Muzani (May Allah be pleased with him) reported:
The Messenger of Allah (ﷺ) said, "A man speaks a good word without knowing its worth, Allah records for him His Good Pleasure till the day he will meet Him; and a man utters an evil word without realizing its importance, Allah records for him His displeasure till the day he will meet Him."[Imam Malik and At-Tirmidhi].
App reference: Book 18, Hadith 6
Arabic/English book reference: Book 18, Hadith 1516