If we see someone about to sin, we have a mitzva to admonish them. These potential sins might include committing adultery, cheating at work, or getting involved in a pointless dispute.
The rebuke must be motivated by a sense of responsibility and love, not by arrogance or hatred. As it says, “You shall not hate your brother in your heart. Reprove your kinsman but incur no guilt because of him . . . Love your fellow as yourself; I am the Lord” (Leviticus 19:17-18). Therefore, we must first make it very clear that we value and love the other person. Only after this has been done may we reprimand. We must do so very carefully, privately and with great sensitivity, as one never knows what might be a delicate or painful issue. We should also bear in mind that we may have misinterpreted something.
Rebuking is always somewhat unpleasant and complicated. Nevertheless, as long as there is some chance it will be effective, it is a mitzva. Sometimes a rebuke can save someone from unknowingly destroying their family or from other catastrophes. Sometimes a person does not know proper work etiquette; if someone does not let them know what they are doing wrong, they will be fired and ignorant of what needs to change to avoid the situation repeating itself. Sometimes a person is unaware they have body odor, or that they speak in a hurtful way. They do not understand why they have no friends and why their spouse is growing distant. Therefore, the mitzva of rebuke is to help the person, in this world and the next.
The Sages tell us that if we might be able to help someone by criticism but do not do so, in a sense we are an accomplice to sin. The more influence we have with someone, the greater our obligation to rebuke them. In the words of the Talmud (Shabbat 54b), “If someone is in a position to object to the bad behavior of his household members but refrains from doing so, he is punished for the behavior of the household members. If it is the people of his city, he is punished for the behavior of the people of his city. If it is the people of the entire world, he is punished for the behavior of the people of the entire world.”
