If someone is not behaving properly, it is a mitzvah to correct his behavior. We must do so even repeatedly, since the Torah says, “hochei’ach tochiach,” which is often translated as “you shall surely rebuke,” but which also means, “you shall repeatedly rebuke.” (See Talmud Baba Metzia 31a.)
Our verse continues, “and you shall not bear a sin because of him.” These words warn us to rebuke others properly. As we will see in the next mitzvah, it is a sin to needlessly shame others, so we are warned to correct others without public embarrassment. (More about this in the next mitzvah).
Failing to rebuke others at all can likewise cause us to “bear a sin.” Here are two ways:
(1) Our previous mitzvah tells us not to secretly loathe others. If we have a problem with others because of their misdeeds, we should tell them in the hope of correcting their behavior, rather than risk violating the prohibition against hating them in our hearts;
(2) If one has the ability to correct another’s behavior and fails to do so, he bears partial responsibility for the misdeeds he could have prevented. We see this from the story of the “cow of Rabbi Elazar ben Azariah.” The Talmud in Shabbos (54b) discusses how the cow belonging to Rabbi Elazar’s neighbor used to go out on Shabbos wearing a forbidden type of strap. The cow was called by Rabbi Elazar’s name because he never tried to correct his neighbor’s behavior.
We see from all this that if one properly rebukes others, he can avoid all sorts of trouble!
The underlying rationale for this mitzvah is to make peace. If one acts out in public but is gently corrected in private, the two parties can reconcile. If one keeps the rebuke inside, it will just build up into resentment and hatred.
It is only a mitzvah to try to correct someone when we think the other person might listen. If a person knows that the rebuke will be ignored, he should keep it to himself. Proverbs 9:8 tells us, “Don’t rebuke a scoffer; he’ll only hate you for it. But if you rebuke a wise person, he’ll love you for it.” (See Talmud Yevamos 65b.) Of course, when our own behavior is corrected, we should strive to act like wise people and appreciate the intervention!
This mitzvah applies in all times and places. It is discussed in the Talmud in tractate Brachos on page 31a, in tractate Shabbos on 54b-55a, and elsewhere. It is codified in the Mishneh Torah in the sixth chapter of Hilchos Deos. This mitzvah is #205 of the 248 positive mitzvos in the Rambam’s Sefer HaMitzvos#72 of the 77 positive mitzvos that can be fulfilled today as listed in the Chofetz Chaim’s Sefer HaMitzvos HaKatzar.