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
175. It is a negative commandment “do not make a false prophecy in the Name of G-d”
As it states in Devarim (Deuteronomy) 18:20, “but the prophet who speaks in My name which I did not command him to speak.” This means that no person shall say words were prophetically given to him by G-d when G-d did not speak them. A person who transgresses this and prophesizes falsely is given the death penalty of strangulation.
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 