Is it forbidden and unacceptable for a father to spend on his children, give their alms (sadaqat), perform their 'umrah, and pay their zakat from money suspected of being usurious?

Working in usurious banks is not permissible. If the father possesses lawful wealth other than his earnings from the usurious bank, then the permissibility of dealing with him regarding his wealth requires elaboration. The ruling on children taking from their father's money, if all his earnings are from usurious banks, has been previously explained.

It is permissible for one who has taken from the father's mixed wealth, or due to his poverty, to give charity from it, perform Hajj, and other good deeds, and he will be rewarded for that. Unlawful wealth is not subject to Zakat because it is not owned by the one who possesses it; rather, it must be disposed of.