Negative commandment · Lo Ta’aseh #303 of 613
Not to embarrass any Jewish person
שלא להלבין פני אדם מישראל
The verse · Vayikra 19:17
לֹא־תִשְׂנָא אֶת־אָחִיךָ בִּלְבָבֶךָ הוֹכֵחַ תּוֹכִיחַ אֶת־עֲמִיתֶךָ וְלֹא־תִשָּׂא עָלָיו חֵטְא
“Thou shalt not hate thy brother in thy heart: thou shalt certainly rebuke thy neighbour, and not suffer sin on his account.”
The Rambam’s words
Not to embarrass any Jewish person, as [Leviticus, ibid.] states: "You shall surely rebuke your neighbor and not bear a sin because of him."
שלא להלבין פני אדם מישראל, שנאמר "הוכח תוכיח את עמיתך, ולא תישא עליו חטא" (ויקרא יט,יז).
Why · Sefer HaChinuch #240
To not whiten the face of an Israelite
“The root of the commandment is well-known — since embarrassment is very painful for the creatures — there is nothing greater than it. Therefore G-d prevented us from causing so much pain to His creatures, since it is possible to rebuke them in private and not to embarrass the sinner so much.”
Who & when
“And [it] is practiced in every place and at all times.”
Where in the Mishneh Torah
Hilchot One Who Injures a Person or Property הלכות חובל ומזיק