LEV602 [Verbal abuse is objectionable] even when it relates to a mitzvah, for Scripture states [this verse]: "Continually reprove your fellowman" – and our Sages of blessed memory commented (Arachin 16b): "Even if his face changes color? Therefore it states [this verse]: 'but do not bring a sin upon yourself [when reproving] him.'" From all of the above you can see how far–reaching this prohibition is and how harsh is its punishment.