What is the ruling on money acquired by a father from working in usurious banks for many years, all of which was spent on living expenses, and is seeking forgiveness and repentance sufficient, or is he required to estimate this money and donate it, and is his current money from working in an Islamic bank considered lawful, and is it permissible for the children to eat from this money, and what is the ruling on items he bought with unlawful money if they are still present, and is it permissible for children to benefit from their father's money for study and training expenses if part of it is from previously unlawful earnings?

The answer can be summarized in the following points:

Firstly: If your father has no source of income other than his salary, then there is no blame upon him for what he spent on himself and his family to the extent of their need. This is because it is permissible for a poor person to take from unlawful money to the extent of his need, and it becomes lawful for him, and he is not required to return compensation. It is hoped that there will be no blame upon him for benefiting from his salary if he is unable to earn a lawful living and finds no alternative for spending on his essential needs and those he supports. He is not required to give away his salary from past years. He should engage in abundant seeking of forgiveness, righteous deeds, and charity. He must be informed of this, or someone should be appointed to advise him.

Secondly: There is no harm in working in Islamic banks that adhere to Sharia regulations, and there is no harm in benefiting from the salary earned from them.

Thirdly: There is no harm in your benefiting from the lawful money your father possesses. What he did previously has no bearing on the earnings he receives from a lawful job, as the unlawful aspect pertains to his own responsibility and does not affect his permissible funds.