Are social security pension funds permissible or forbidden if their source was the deceased father's work in a bank?

The aforementioned pension is divided into two parts: a part contributed by the deceased from his salary, and a part added by the state. There is no harm in benefiting from the part added by the state.

As for the part contributed by the deceased, it should be considered:

1. If the bank was usurious and the deceased knew of its prohibition: The salary is forbidden, and one must dispose of it by giving it to the poor and needy, unless the heirs are poor and in need, in which case they may benefit from it, based on Al-Nawawi's statement: "And if he gives it—the unlawful money—to the poor, it is not forbidden for the poor, but rather lawful and good. And he may give it as charity to himself and his family if he is poor." The death of the inheritor does not make unlawful money lawful for the heir.

2. If the bank was Islamic, or if it was usurious but the deceased was ignorant of the prohibition of working there: There is no harm in benefiting from the entire pension.

One should consult scholars in the questioner's country for clarification.