What is the ruling on the salary of a father who works teaching music, despite his repeated attempts to change his profession and his religious commitment, and what is the ruling on the son benefiting from this money, knowing that the subject he teaches includes religious and national songs and praise of the Prophet?

Earning from musical instruments is forbidden. However, if a person reaches a state of dire necessity and cannot find any other work, such that they fear perishing or causing those they support to perish, then it is hoped that they will be excused, while still being obligated to search for lawful work. Allah knows best the specific circumstances of the questioner.