John Gill Bible Commentary

Every vow, and every binding oath to afflict the soul,.... By fasting, as Aben Ezra observes; as when a vow was made, or a person bound herself by an oath to abstain from such and such food, or to fast on such a day; to keep a fast which was not appointed, to set apart a day for fasting, besides the grand and general fast on the day of atonement: Jarchi from hence gathers, that a man only makes vows of afflicting the soul, or vows of fasting; but this is not said by way of limitation and restriction, but by way of amplification and illustration, giving a particular instance, by which others may be judged of: her husband may establish it, or her husband may make it void, just as he pleased; and this power an husband had, to prevent confusion in the family, and trouble in the affairs of it, by vowing abstinence from such and such food, or from such and such liquor, and the like; and to prevent running into expenses he was not able to answer, by vowing and dedicating, this and the other to holy uses, for sacrifices, and repairs of the temple, and the like.