Curse a Jew

 Chinuch (Kedoshim # 231) To not curse a Jew, whether a man or a woman: To not curse an Israelite, whether a man or a woman; and even though he does not hear the curse, as it is stated, “You shall not curse the deaf” — and the explanation comes about this that it is one who does not hear your curse. And so did Onkelos translate it. And the language of Sifra, Kedoshim is “I only have a deaf person, from where do I include every man? Hence we learn to say, ‘among your people, you shall not maledict.’ If so, why does it state, ‘deaf?’ Just like a deaf person is unique that he is alive — to exclude the dead that is not alive.” Even though we do not have the power to know in which way a curse impacts upon the one cursed, and with what power within speech there is to bring that impact upon him, we know more generally that people are concerned about curses — whether Israel or other nations — and say that curses of people, and even curses of commoners, have an impact on the one cursed and attaches malediction and distress to him. And since we know this thing from the mouth of the creatures, we will say that it is from the roots of the commandment that God prevented us from injuring others with our mouths, just like He prevented us from injuring them with action. 

Chinuch (Kedoshim # 231) To not curse a Jew Curses of people, and even curses of commoners, have an impact on the one cursed and attaches malediction and distress to him. And since we know this thing from the mouth of the creatures, we will say that it is from the roots of the commandment that God prevented us from injuring others with our mouths, just like He prevented us from injuring them with action. And similar to this did they say, “A covenant is made with the lips” — meaning to say that there is power in the words of a person’s mouth.

Chinuch (Kedoshim # 231) To not curse a Jew, whether a man or a woman: And Rambam said  as the reason of the commandment that it is in order that the soul of the one that curses not be moved to vengeance and that he not become used to anger. And he wrote at further length about this in his book. And it appears to me from his words that, in his opinion, he does not see any injury to the one cursed from the curse, but rather that the Torah is distancing the matter from the perspective of the one that curses — that he not accustom himself to vengeance and anger and to lowly traits. And we shall accept all the words of our rabbis, though our hearts hold more of what we have written.