וַיַּשְׁכִּימוּ בַבֹּקֶר, וַיִּשָּׁבְעוּ אִישׁ לְאָחִיו; וַיְשַׁלְּחֵם יִצְחָק, וַיֵּלְכוּ מֵאִתּוֹ בְּשָׁלוֹם
(26:21)
After Yitzchak and Rivka were originally expelled by Avimelech, he realised that the success of his people was dependant on Yitzchak’s presence so he sent a party to invite him back. Yitzchak chastises them for their earlier behaviour. They make peace and he agrees to go back. Chazal in Sifri learn from here that ‘תוכחה מביאה לידי שלום’.
The Gemora in Erechin 16b discusses the Mitzvah of הוכח תוכיח את עמיתך and concludes that one is obligated to rebuke a sinner, and if he does not heed your words, to continue rebuking until the point that he hits you.
However, the Gemora in Yevamos 65b teaches that ‘just as there is a Mitzvah to offer rebuke when it will be heeded, so too there is no Mitzvah if it is obvious it will not help’. This would seem to contradict to the Gemora in Erechin that obligates us to rebuke until the point the sinner lashes out; according to our understanding of the Gemora in Yevamos one would never reach that point.
In Hilchos De’os 6:7, the Rambam writes that the whole purpose of the Mitzvah of תוכחה is to ensure the complete reversal of behaviour of the sinner, and to ‘bring him back to the good’. Therefore, should a person evaluate the situation and come to the conclusion that the sinner is beyond the point of no return and that no amount of rebuke will help bring him ‘back to the good’, the Mitzvah does not begin. This is what is being referred to in the Gemora in Yervamos. If, however, one is confident that he can get through to the person, even though it may take some time and more than one attempt, he is obligated to rebuke until the point that the sinner strikes him, as required by the Gemora in Erechin.
The Nimmukei Yosef offers a different answer. He says that the Gemora that requires one to rebuke until the point that the sinner lashes out is referring to rebuke of an individual. However, the Gemora in Yevamos that informs us that it is a Mitzvah not to rebuke when it will go unheeded is referring to rebuke of an entire community (although the N.Y. says that even with a community, it is still necessary to make one attempt at rebuke).
There is another factor to consider. The Gemora in Beitza 31a states,
מוטב שיהיו שוגגין ואל יהיו מזידין, it is better not to inform an accidental wrong-doer of his sin if he will continue to do it with intent. This would mean that even with an individual sinner, if he is currently unaware of his transgression and would continue behaving thus even if advised of his wrongdoing, there is no Mitzvah of תוכחה. (The Gemora points out, however, this is not so with something that is stated explicitly in the Torah; no-one can claim to not know about such a misdeed.)
In Shulchan Aruch §608, the Rem”a rules in accordance with the Nimukei Yosef; concerning an individual, one must rebuke until he hits you, and regarding an entire community, if it is estimated that the rebuke will not work, one is obligated to offer one attempt at rebuke and no more. If the sin observed is being carried out inadvertently (and it is estimated that the rebuke will not change anything), there is no Mitzvah, unless it is something that is explicitly stated in the Torah.
