What is the ruling regarding a woman who vowed to name her newborn after her brother, then broke her vow after giving birth to a male?

Scholars have differed regarding a vow concerning a permissible act, such as the name you vowed for the child, whether it becomes binding and necessitates fulfillment or not. The Hanbalis are of the view that it becomes binding, and the one who made the vow has the choice between fulfilling it or offering an expiation for an oath (kaffarat yamin). Whereas the Malikis, Shafi'is, and Hanafis are of the view that it does not become binding and does not necessitate fulfillment. The preponderant opinion is that it does not become binding. Therefore, it is permissible to change your mind about naming the child with the vowed name, and there is no sin upon you. However, if you offer an expiation for an oath, it is better as a way of resolving the difference of opinion.