"Bhikkhus, these are the four misconducts by way of speech. What are the four? False speech, divisive speech, harsh speech, and idle chatter — these are the four misconducts by way of speech.

Bhikkhus, these are the four good conducts by way of speech. What are the four? Truthful speech, speech that is not divisive (promoting harmony), gentle speech, and thoughtful speech — these are the four good conducts by way of speech."

Related Teachings:

Five factors of well-spoken speech (AN 5.198) - The Buddha shares on the five factors of well-spoken speech

Guarding against irritability in body, speech, thought (DhP 231, 232, 233, 234) - The Buddha is advising against getting irritated, for bad conduct by way of body, speech or thoughts fuels the fetter of ignorance.