Musar sur Le Lévitique 25:7

And anyone who causes pain to a fellow Jew transgresses a prohibitive command, as it is said: "And you shall not wrong one another but you shall fear the Lord" (Lev. 25:17), and this phrase "you shall not wrong" is said concerning wronging by words (Baba Mezi'a 58b). And our Rabbis, of blessed memory, said: "All gates are closed to hearing accusations against the repentant except the gate of wronging a fellow Jew" (Ibid. 59a). Therefore, should one be very careful not to cause pain to his companion in any way — not by deeds and not by words.