The phrase "Dibur B'nachat" (דיבור בנחת) literally means "speaking calmly" or "speaking gently". It is a central Jewish ethical concept deeply rooted in the Iggeret HaRamban (the Epistle of Nachmanides), which urges a person to speak all their words gently to everyone at all times to avoid the destructive trait of anger. 

The book, Dibur B'nachat (דיבור בנחת), it is a well-known Torah work authored by Rabbi Shlomo Ben Avraham Man. It serves as a comprehensive guide on overcoming anger, compiling practical advice, moral lessons, and inspirational stories from Chazal and Torah sages