What is the ruling on selling a work visa issued in the name of a mother who passed away before knowing about it?

Selling a work visa (permit) is impermissible due to the deception, fraud, and unlawful acquisition of wealth involved. If the mother was unaware of its impermissibility, she is excused due to her ignorance. However, the heirs must return the money acquired from selling the visa to the worker, excluding any fees paid or the cost of effort expended in obtaining it.