Noble Eightfold Path
Right speech is the first principle of ethical conduct in the eightfold path. Ethical conduct is viewed as a guideline to moral discipline, which supports the other principles of the path. This aspect is not self-sufficient, however, essential, because mental purification can only be achieved through the cultivation of ethical conduct. The importance of speech in the context of Buddhist ethics is obvious: words can break or save lives, make enemies or friends, start war or create peace.
Buddha explained right speech as follows:
Positively phrased, this means to tell the truth, to speak friendly, warm, and gently and to talk only when necessary.