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
28. It is a negative commandment “Not to make a bruise or a cut on one’s skin for idol worship for the death of one’s relative”
As it states in Devarim (Deuteronomy) 14:1, “Do not give yourself a bruise.” A person that gives himself a cut for his dead relative, also transgresses this negative commandment, whether he does it with his own hand or with a utensil. In idol worship, if it is done with a utensil, he gets lashes, and if it is done by hand, he is not held liable [but it is still forbidden]. Included in the law of “not giving yourself a bruise” is a prohibition not to separate into groups. By groups, it means, not to have two courts in one city – one following these customs and another following different customs.
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 