Negative Commandment #165
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
165. It is a negative commandment "do not act on omens."
As it states in Vayikra (Leviticus) 19:26, "do not act on basis of omens." For example, those who say, 'my bread fell from my mouth,' or 'my cane fell from my hand. Therefore, I will not go to such and such a place today.' This includes one who makes signs for himself like, 'if such and such will happen to me, then I will do such and such.' If a person acts on basis of an omen like these, he transgresses this negative commandment.
This applies in all places and at all times, for men and for women.