Regarding any vow or any oath involving an abstinence vow to practice self-denial, her husband should establish it or her husband should annul it.
~Numbers 30:13

Under Mosaic Law, if a married Israelite woman made a vow to God, she had to communicate that vow to her husband that same day.

As head of the household, her husband had authority to either establish or annul the vow.

At first view, it seems God did not trust married women to make their own decisions, which could offend some of us.

However seeing it from a financial perspective it makes sense, because it was the husband’s responsibility to make ends meet and so any vow incurred by his wife might affect the family as a whole.

Let’s say for example that the wife vowed to donate 20% of the harvest instead of just the 10% the tithe required.

Now let’s imagine that in that year it did not really rain so there was not much grain to harvest and now they have more than five starving kids to feed.

It would make sense that the husband had the authority to annul his wife’s vow, ‘bearing the consequences of her guilt,’ (Nu. 30:15).

By requiring the vow to be communicated to her husband, the wife was also pressed to think twice before saying compromising things out of sentimentalism that were not thoroughly calculated.

Christian women are not obligated to have their husband’s approval before they enter spiritual compromises.

Many women in the first century converted to Christianity even when their husbands were unbelievers (1 Pet. 3:1).

However, the husband is still considered head of the household, so it is still wise on the part of a wife to communicate her decisions to him either before or soon after taking them, yielding to his advice whenever reasonable (Prov. 13:10; Acts 5:29; 1 Cor. 11:3).

She would thereby demonstrate respect for both Jehovah and her spouse and contribute to the whole family’s success.