Is it obligatory to fulfill a vow to wear an "Isdal" (a loose, modest garment) after it became clear that the reason for the vow—hearing exam results incorrectly—was not true, knowing that the family opposes it, but there is a desire to fulfill it?

The legal hijab is an obligation that may not be abandoned or delayed. Adherence to it is required even if no vow has been made concerning it, because, according to the majority of scholars, a vow concerning an obligation is not binding.

The hijab does not necessitate a specific garment. Any clothing that meets the specifications of the legal hijab is suitable to be a hijab. However, most of the skirts known today, and similar garments, are not suitable as a hijab.

It is not permissible to obey parents in not wearing the hijab, because there is no obedience to a creature in disobedience to the Creator.