And even so, if one sees a degrading trait in a person, such as haughtiness or anger or other evil traits or that he neglects Torah study and the like, it is proper for him to tell this to his son or to his students, and to exhort them not to keep company with him so as not to learn from his deeds. For the root of the Torah's exhortation against lashon hara, even when [what is said] is true, applies when one's intent is to shame his friend and to rejoice in his shame. But if his intent is to guard his friend against learning from his [the sinner's] ways, it is obviously permitted, and is also accounted a mitzvah. Yet, in this case and the like, it seems that it is a mitzvah for the teller to explain the reason that he is speaking demeaningly of his friend, so that the listener not err in permitting through him [the speaker] even more [leniency] than this, and also so that he [the listener] not come to wonder how he [the speaker] can thus contradict himself. For at one time he tells him that it is forbidden to speak [lashon hara] even if it is true (as will be explained in Principle 9, that it is a great mitzvah to separate one's young children from this sin), and now, he himself speaks it! (A parallel can be found in Shulchan Aruch, Yoreh Deah 242, as to whether on Shabbath eve certain things may be permitted, which other poskim forbid, and the like.)
וְאַף עַל פִּי כֵן (מא) אִם רוֹאֶה אָדָם (מב) בִּאֶחָד מִדָּה מְגֻנָּה, כְּגוֹן: גַּאֲוָה אוֹ כַּעַס אוֹ שְׁאָרֵי מִדּוֹת רָעוֹת אוֹ שֶׁהוּא בַּטְלָן מִתּוֹרָה וְכַיּוֹצֵא בָּזֶה, נָכוֹן לוֹ לְסַפֵּר דָּבָר זֶה לִבְנוֹ אוֹ לְתַלְמִידָיו וּלְהַזְהִירָם, שֶׁלֹּא יִתְחַבְּרוּ עִמּוֹ, כְּדֵי שֶׁלֹּא יִלְמְדוּ מִמַּעֲשָׂיו, כִּי הָעִקָּר מַה שֶּׁהִזְהִירָה הַתּוֹרָה בְּלָשׁוֹן הָרָע, אֲפִלּוּ עַל אֱמֶת, הוּא אִם כַּוָּנָתוֹ לְבַזּוֹת אֶת חֲבֵרוֹ וְלִשְׂמֹחַ לִקְלוֹנוֹ, אבָל אִם כַּוָּנָתוֹ לִשְׁמֹר אֶת חֲבֵרוֹ שֶׁלֹּא יִלְמֹד מִמַּעֲשָׂיו (מג) פָּשׁוּט דְּמֻתָּר וּמִצְּוָה נַמֵּי אִיכָּא {גם כן יש}. אַךְ בְּאֹפֶן זֶה וְכַיּוֹצֵא בָּזֶה נִרְאֶה, דְּמִצְוָה לְהַמְסַפֵּר לְבָאֵר הַטַּעַם, לָמָּה מְסַפֵּר בִּגְנוּתוֹ שֶׁל חֲבֵרוֹ, כְּדֵי שֶׁלֹּא יִטְעֶה הַשּׁוֹמֵעַ לְהַתִּיר עַל יָדוֹ יוֹתֵר מִזֶּה, וְגַם שֶׁלֹּא יָבוֹא לִתְמֹהַ עָלָיו, שֶׁהוּא סוֹתֵר אֶת עַצְּמוֹ, כִּי פַּעַם יֹאמַר לוֹ, שֶׁאָסוּר לְסַפֵּר אֲפִלּוּ עַל אֱמֶת, כְּמוֹ שֶׁיִּתְבָּאֵר לְקַמָּן בִּכְלָל ט', שֶׁמִּצְוָה רַבָּה הִיא לְהַפְרִישׁ בָּנָיו הַקְּטַנִּים מִּזֶּה הֶעָוֹן, וְעַתָּה הוּא מְסַפֵּר בְּעַצְּמוֹ, (וּבְהַאי גַּוְנָא אִיתָא {וכיוצא בזה כתוב} בְּשֻׁלְחָן עָרוּךְ יוֹרֶה דֵּעָה, אִם הוּא מַתִּיר דָּבָר, שֶׁיֵּשׁ פּוֹסְקִים לְאִסוּר בְּעֶרֶב שַׁבָּת וְכַיּוֹצֵא בָּזֶה).
And even so, if one sees a degrading trait in a person, such as haughtiness or anger or other evil traits or that he neglects Torah study and the like, it is proper for him to tell this to his son or to his students, and to exhort them not to keep company with him so as not to learn from his deeds. For the root of the Torah's exhortation against lashon hara, even when [what is said] is true, applies when one's intent is to shame his friend and to rejoice in his shame. But if his intent is to guard his friend against learning from his [the sinner's] ways, it is obviously permitted, and is also accounted a mitzvah. Yet, in this case and the like, it seems that it is a mitzvah for the teller to explain the reason that he is speaking demeaningly of his friend, so that the listener not err in permitting through him [the speaker] even more [leniency] than this, and also so that he [the listener] not come to wonder how he [the speaker] can thus contradict himself. For at one time he tells him that it is forbidden to speak [lashon hara] even if it is true (as will be explained in Principle 9, that it is a great mitzvah to separate one's young children from this sin), and now, he himself speaks it! (A parallel can be found in Shulchan Aruch, Yoreh Deah 242, as to whether on Shabbath eve certain things may be permitted, which other poskim forbid, and the like.)