when making a vow, it is important that other people understand what is being said.
it is part of the conversation when buying and selling
but they will also pay attention when you shun your daughter.
using vows as part of the haggling banter, everyone knows that it is just how the conversation goes between buyer and seller. not really intended as a vow. also on this page is a case where a woman vowed that her daughter should not benefit from her (who knows what the daughter had done...) but the vow was cancelled as the mother would never have vowed this if she knew that other people would know about the vow.