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
29. It is a negative commandment “Do not swear in vain”
As it states in Shemos (Exodus) 20:7, “You shall not take the name of G-d in vain.” A swear made in vain can be divided into four categories: 1) If one swears to change something that is known, like swear that a man is a woman, or a rock is gold. 2) If one swears with no purpose, like swearing that a rock is a rock. 3) If one swears not to perform a commandment. 4) If one swears to do something that is impossible, like not to sleep for three days in a row or not to taste food for seven days in a row. On all of these swearings: if he swore knowingly, he is to receive whipping. If he swore accidentally, he receives no penalty. If a person says a blessing that is not required or states G-d’s Name for no purpose, he transgresses this commandment.
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 