Nedarim, Chapter Ten, Mishnah 1. This chapter presents us with part of the Torah's portion dealing with vows - the law of annulling vows. Annulment of vows (hafarah) is different from dissolution of vows (hataras nedarim), and we must first clarify the difference between them.
Hafarah and Hataras Nedarim - what is the difference:
Dissolution of vows (hataras nedarim): A sage or a court finds grounds to dissolve the vow and render the item permitted, based on the idea that had the person known, he never would have made the vow to begin with. This is a "petach" (an opening) or "charatah" (regret) - the one who vowed regrets having made the vow, and the dissolution uproots the vow from its very inception, to the point that we say it never took effect at all.
Annulment of vows (hafarah): An authority granted to a father or a husband regarding the vows of his daughter or his wife. The annulment does not uproot the vow retroactively; rather, it cancels it from this point forward - from the moment they heard the vow and annulled it, the vow no longer takes effect.
The time for annulment:
The annulment must be done on the day the vow was heard, before nightfall. If the father or husband did not annul it on that day, the vow stands and has been upheld. Similarly, if before the end of the day the father or husband expressed his wish that the vow remain in force, the vow stands, and they can no longer annul it.
Who is a "na'arah ha'me'orasah" (a betrothed maiden):
A "na'arah" is a girl who has reached the age of mitzvos and has developed the physical signs of maturity. Six months later she becomes a "bogeres" and leaves her father's authority, but as long as she is still classified as a "na'arah," during those first six months, her vows are subject to her father's authority.
Our Mishnah deals specifically with a betrothed maiden - one who has become betrothed to a man but has not yet been married and has not moved in with him, as would happen upon marriage, and she is therefore still in her father's home. In this in-between state, the authority over her vows is divided between her father and her husband.
"Na'arah ha'me'orasah - aviha u'ba'alah mefirin nedareha" - a betrothed maiden: her father and her husband annul her vows:
The two of them together annul her vows, and they have the power to effect an annulment and cause her vows not to be binding.
"Hefer ha'av v'lo hefer ha'ba'al, hefer ha'ba'al v'lo hefer ha'av - eino mufar" - if the father annulled and the husband did not annul, or the husband annulled and the father did not annul, it is not annulled - the annulment of only one of them is ineffective, and the vow is not annulled. The participation of both of them is required in order for the vow to no longer be binding.
"V'ein tzarich lomar she'kiyeim echad meihen" - and it goes without saying if one of them upheld the vow - that is, if one of the two upheld the vow, meaning he expressed his wish that it remain in force, then obviously the vow stands, regardless of what the other one did.
In summary: In this Mishnah we learned the difference between dissolution of vows, which uproots the vow from its very inception, and annulment of vows, which cancels it only from this point forward and only on the day it was heard. We clarified the status of a betrothed maiden, who stands simultaneously under her father's authority and under her husband's authority, and we learned that annulling her vows requires both of them together: an annulment by one of them alone is ineffective, while upholding the vow by one of them alone leaves the vow in force.