Is it permissible for a person to take money from his father, who works as an accountant in a bank, and is it permissible for him to marry from it, based on the statement of one of the brothers that this money is unlawful and there is no evidence to prohibit that except disbelief?

The money earned by the father from working in a usurious bank is unlawful (haram) money. It is not permissible for the son to take anything from it except in cases of dire necessity or extreme need, such as the son's poverty or his need to get married. In such cases, he may take from it only what is sufficient to avert that necessity. As for other situations, this money must be spent on the welfare of Muslims, such as assisting the poor and needy and building hospitals.