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
First Section – the Positive Commandments
39. It is a positive commandment to fulfill vows or oaths that one has verbally taken upon himself
As it states in Devarim (Deuteronomy) 23:24, “Guard and do what has passed your lips, as you have vowed.” It also states in Bamidbar (Numbers) 30:3, “All that comes from your mouth, you shall do.”
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 