Musar על בבא מציעא 117:7

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.

Our sages of blessed memory already said "verbal oppression is more severe than monetary oppression..." (ibid). This is even more so, if the shaming is done in public as we learned explicitly: "one who whitens his neighbor's face (shames him) publicly has no portion in the World to Come" (Avot 5:11), and Rabbi Chisda taught (Bava Metzia 59a): "all the gates [of prayer] were locked except the gates of [the cries of] verbal oppression". Rabbi Eliezer taught "for every sin, the Holy One, blessed be He, exacts payment through a messenger except for the sin of verbal oppression".