Is it necessary to offer expiation for a vow to abstain from listening to music every time one returns to it, or only once?

She must stop listening to music absolutely. This is even more confirmed after making a vow (Nathr), because the punishment for violating a vow is severe. Listening to music corrupts the heart and breeds hypocrisy. Those who listen to it prefer it over the Qur'an, and this is a form of hypocrisy. Allah may hasten the punishment for those who listen to singing and musical instruments in this world, for the Prophet, peace and blessings be upon him, warned of being swallowed by the earth, transformed, and pelted with stones if singing women and musical instruments become widespread and alcohol is consumed. He mentioned a hadith about people who drink alcohol and listen to musical instruments, so Allah will cause the earth to swallow them and transform them into apes and pigs. A believer must avoid what angers Allah. She owes a single expiation for not fulfilling her vow.