Negative Commandment #28
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.