The 205th mitzvah is that we are commanded to admonish a person who is performing a transgression or who is preparing to do so. One must verbally warn him and admonish him. We are not allowed to say, "I will not sin; and if someone else sins, that is between him and G‑d." This [attitude] is contrary to Torah. Rather, we are commanded not to transgress, nor to allow another Jew to transgress. If a person is preparing to transgress, each individual is commanded to admonish him and to prevent him [from transgressing], even if there has not been testimony which would be sufficient for him to be punished.
The source of this commandment is G‑d's statement (exalted be He),1 "You must admonish your neighbor."
Also included in this commandment is that we should complain to a person who has done wrong to us. We should not bear a grudge and consider him to be a sinner. Rather, we are commanded to verbally complain to him in order that nothing should remain in our heart [against him].
In the words of the Sifra, "What is the source of the law that even if you admonish someone four or five times that you should continue to admonish him? From the phrase, 'hochei'ach to'chiach.'2 One might think that one could admonish him to the point that his facial features change3 — the verse therefore continues,4 "And not bear sin because of him."
Our Sages5 explained that this commandment is incumbent on every individual; even a person on a low level to someone on a higher level.6 Even if one is cursed or insulted he should not desist, nor stop admonishing unless he is struck physically, as explained by our Sages from the Oral Torah,7 "[One must reprimand] until one receives physical blows."
This mitzvah has conditions and laws which are explained in various places in the Talmud.
