Mefárszemim

Furthermore, they said: One exposes the hypocrites due to the desecration of God’s name, so others will not think that they are truly righteous and that their deeds bear imitating, as it is stated: “When a righteous man turns from his righteousness and commits iniquity, I will lay a stumbling block before him” (Ezekiel 3:20). That is, when people do not know that someone is wicked to the core, he causes other people to err and this desecrates the name of God when it is revealed. The repentance of utterly wicked people prevents suffering from coming upon them. And although the sentence of judgment has already been signed against them for suffering, their repentance prevents them from being punished.

At first, a person who admonishes a colleague should not speak to him harshly until he becomes embarrassed as [Leviticus 19:17] states: "[You should]... not bear a sin because of him." This is what our Sages said: Should you rebuke him to the point that his face changes [color]? The Torah states: "[You should]... not bear a sin because of him."
From this, [we learn that] it is forbidden for a person to embarrass a [fellow] Jew. How much more so [is it forbidden to embarrass him] in public. Even though a person who embarrasses a colleague is not [liable for] lashes on account of him, it is a great sin. Our Sages said: "A person who embarrasses a colleague in public does not have a share in the world to come."
Therefore, a person should be careful not to embarrass a colleague - whether of great or lesser stature - in public, and not to call him a name which embarrasses him or to relate a matter that brings him shame in his presence.
When does the above apply? In regard to matters between one man and another. However, in regard to spiritual matters, if [a transgressor] does not repent [after being admonished] in private, he may be put to shame in public and his sin may be publicized. He may be subjected to abuse, scorn, and curses until he repents, as was the practice of all the prophets of Israel.

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And all of these dinim that we have set down apply only to a man who is wont to regret his sins. But if you have probed his ways and seen that the fear of G–d is not before his eyes and that he always persists in a way that is not good — such as one who divests himself of the yoke of Heaven or is unheedful of a transgression which every one of his people knows to be a transgression — that is, whether the sin you wish to reveal has been committed deliberately many times by the sinner or he often transgresses deliberately a different sin which is known by all to be a sin — then it is apparent that it is not because his evil inclination overpowered him that he transgressed the word of the L–rd, but that he does as his heart sees fit and the fear of G–d is not before his eyes. Therefore, it is permitted to shame him and to speak demeaningly of him, both before him and in his absence. And if he does something or says something which can be judged either in the scales of merit or in the scales of guilt, he must be judged in the scales of guilt, since he has shown himself to be an absolute evildoer in his other affairs. And thus have our Rabbis said (Bava Metzia 59a): "'And you shall not wrong, one man, his fellow [amito]' (Vayikra 25:17) — 'a people who is with you' [am ito] in Torah and mitzvoth — do not wrong him with words!" And if one does not direct his heart to the word of the L–rd, it is permitted to shame him for his deeds, to make known his abominations, and to spill scorn upon him. And they said further (Yoma 86b): "Flatterers are exposed because of the desecration of the Name [that they engender]." And much more so if one reproved him for [his sin] and he did not desist from it, is it permitted to expose him and to reveal his sin in "the public gate" and to spill scorn upon him, until he returns to the good, as the Rambam has written in the end of Hilchoth Deoth 5. But it is important not to forget certain considerations that this entails, which I have written of in Be'er Mayim Chayim.

If a man saw someone harming his friend, whether robbing him, wronging him, or causing him damage, whether the one robbed or caused damage knew of it or not — or if he shamed him or aggrieved him, or wronged him with words — and it became known to him clearly that he did not return the theft or reimburse him for the damage and did not beseech him to forgive his transgression — even if he saw this thing by himself, he can relate it to others in order to help the one who was wronged and to condemn these evil deeds before men; but he must take care that there not be lacking the following seven details which we shall now explain: