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
Second Section – the Negative Commandments
76. It is a negative commandment “do not make your friend stumble over anything.”
As it states in Vayikra (Leviticus) 19:14, “do not put a stumbling block in front of a blind man.” This means to say, if he is ‘blind’ in a certain area and asks for advice, do not give him advice that is improper. This includes anything he may ask about: worldly matters or Torah matters. It is also forbidden to bring someone to him, to help him, or to cause him to come to another person in order to do a sin. It is also forbidden to bring a non-Jew to transgress a Torah law which he is required to be careful to observe (the seven Noahide laws).
This applies in all places and at all times, for men and for women.
4. Be kind to yourself. Speaking badly even about yourself is unethical.
הלכות שמירת הלשון 