Who shames his friend in public is as one who sheds blood
He who shames or insults his friend or any other person in the name of others is as if he had killed him or as if he had killed a human being.
("All the one who was in the presence of his friend in many ways, as if he had shed blood - he said to her: You said, 'Sapphir ka,' we saw her blush and turn pale (translation: He said to him: 'You said, 'Beautiful,' we saw how the red in her face would fade and she would turn pale)" - Baba Matzia, 192b)
Translation
Expression (Hebrew)
הַמַּלְבִּין פְּנֵי חֲבֵרוֹ בָּרַבִּים כְּאִלּוּ שׁוֹפֵךְ דָּמִים
Definition (Hebrew)
הַמְּבַיֵּשׁ אוֹ מַעֲלִיב אֶת חֲבֵרוֹ אוֹ כָּל אָדָם בְּנוֹכְחוּת אֲחֵרִים כְּאִלּוּ הָרַג אוֹתוֹ אוֹ כְּאִלּוּ הָרַג נֶפֶשׁ שֶׁל אָדָם.
("כָּל הַמַּלְבִּין פְּנֵי חֲבֵרוֹ בָּרַבִּים כְּאִלּוּ שׁוֹפֵךְ דָּמִים- אָמַר לֵהּ: שָׁפִיר קָא אָמַרְתָּ, דְּחָזֵינָא לֵהּ דְּאָזֵל סֻמָּקָא וְאָתֵי חִוָּרָא (תַּרְגּוּם: אָמַר לוֹ: יָפֶה אָמַרְתָּ, שֶׁרָאִינוּ אֵיךְ אוֹזֵל הָאֹדֶם מִפָּנָיו וְנִהְיֶה חִוֵּר)"- בָּבָא מְצִיעָא נָח ע"ב)