Sefer Ha’mitzvos Ha’Katzar (The concise book of mitzvos)
By the Chofetz Chaim

This book lists the Torah mitzvos that can be observed today

First Section — the Positive Commandments

72. It is a positive commandment to rebuke a sinner

As it states in Vayikra (Leviticus) 19:17, “Rebuke, you shall surely
rebuke, your friend.” The one rebuking should inform the other person
that he is a sinner and his deeds are bad. The rebuker must also tell
him that he says this only for the sinner’s good and to bring him to
the World to Come. A person is required to rebuke until the sinner
listens to him or until the sinner hits him and says, “I will not
listen to you!” There are early authorities that are lenient about
this, and say he is only required to rebuke until there is an angry
outburst. Even according to the first view, if it is for a Torah law,
the person should estimate that it will be effective for the future,
that he will no longer do this sin.

Even a younger person is required to rebuke an elder. Anyone that has
within their power to rebuke and does not, is guilty of sin.

Even though there is a commandment to rebuke, he should not embarrass
the other person. There is a commandment to accept rebuke and to love
the person who does the rebuking. It is stated in the words of our
Sages of blessed memory, even for a Rabbinic law, if a person
transgresses it willingly, it is allowable to call him a sinner.

This applies in all places and at all times, for men and for women.