The Buddha // Sevitabbasevitabba Suta, Pali Canon

What kind of verbal conduct causes unwholesome states to diminish and wholesome states to increase in one who cultivates it? […]

One abandons malicious speech, and abstains from malicious speech; one does not repeat elsewhere what one has heard here in order to divine these people from those; one reunites those who are divided, is a promoter of friendships, enjoys concord, rejoices in harmony, delights in peace and is a speaker of words that promote unity.