Is it permissible to offer expiation for a vow when one is able to fulfill it but does not wish to, and does expiation nullify the vow in this case?

An expiation does not suffice for a vow of obedience if the one who made the vow is able to fulfill it. He must fulfill it in the manner he vowed, unless he becomes completely and hopelessly unable to fulfill it, in which case an expiation for a broken oath (kaffarat yamin) becomes obligatory upon him. As for a vow of contention (nathr al-lajaj) and a vow concerning permissible matters (nathr al-mubah), the one who made the vow has the choice between fulfilling it or offering an expiation for a broken oath. As for a vow of disobedience, it is forbidden to fulfill it, and its maker must offer an expiation for a broken oath.