What is the ruling on the pension and end-of-service bonus of the husband's father, knowing that he wants to repent and purify his wealth, and that a portion of the pension and bonus was deducted before he knew of the impermissibility of working in the bank? And does he take from it what was deducted before he knew, or does he give it all away?

The original ruling is that working in usurious banks and receiving salaries and bonuses from them is forbidden because they are the result of a prohibited act. Any money not yet received before knowledge of the prohibition is not permissible to benefit from, based on the Almighty's saying: "So whoever receives an admonition from his Lord and desists, he may have what has already passed," which Al-Jassas interpreted as what was received before the prohibition of usury was revealed. However, if one has no other money, it is permissible to take only what suffices for necessity or dire need, and dispose of the remainder by donating it to charitable causes. It is not permissible to work in institutions with mixed activities if that entails engaging in a prohibited act, even if one intends to donate the Haram portion of their salary.