LEV382 Do not curse your fellow Jew. Generally, people are frightened if someone curses them, for they suspect that the curse might harm them. Therefore, just as Hashem forbids us to harm our fellows through our actions, He forbids us to harm them through our words. What is more, man's being has a spiritual component--his soul--and the soul has the power the influence and affect others. The greater the individual and the more he achieves closeness to Hashem—as do tzaddikim and chassidim--the quicker will his words have effect. In addition, if someone curses his fellow, even not to his face, the one who was cursed is likely to hear of it. Hashem wants to minimize strife and see us living in peace with one another. Therefore, He forbids us to curse others. The Rambam writes that this prohibition is a protective measure so that we do not become vengeful and prone to anger. From his explanation it appears that the Torah is not concerned that someone who curses his fellow might thereby harm him. Rather the Torah’s concern here is those who might utter the curses. The prohibition is meant to prevent them from developing the negative character traits of vengefulness and anger.