لَيْسَ الْمُؤْمِنُ بِالطَّعَّانِ، وَلَا بِاللَّعَّانِ، وَلَا الْفَاحِشِ، وَلَا الْبَذِيِّ
A believer is not habitually an abusive critic, a curser, or a person of obscene or vulgar speech.
Source: الترمذي
الطَّعَّانِ describes a habitual fault-finder or verbal attacker; اللَّعَّانِ one who frequently curses; الْفَاحِشِ someone obscene in speech; and الْبَذِيِّ someone vulgar or abusive. The repeated negation singles out each objectionable habit.
The aim is not merely to avoid several forbidden words, but to cultivate speech that does not normalize humiliation, curses, or abusive attacks. Correcting another person's conduct with evidence is different from degrading their dignity.