He replied:

Praise be to Allah. If their wealth contains both lawful and unlawful funds, dealing with them involves doubt. Such dealings cannot be declared unlawful unless it is known that what they give is unlawful for them to give, nor can they be declared lawful unless it is known that what they have given comes from lawful funds. If lawful wealth predominates, dealings with them are not ruled unlawful. If unlawful wealth predominates, some hold that dealing with them is lawful, while others hold that it is unlawful.

As for someone who engages in usury, most of his wealth is lawful, unless some other ground for objection is known. This is because, if he sells one thousand for one thousand two hundred, only the excess is unlawful. If his wealth contains lawful and unlawful funds that have become mixed, the lawful portion does not become unlawful. Rather, he may take an amount corresponding to the lawful portion, just as when wealth belongs to two partners and the funds of one become mixed with those of the other: it is divided between them.

Likewise, someone whose lawful and unlawful wealth has become mixed must remove an amount corresponding to the unlawful portion; the remainder is lawful for him. Allah knows best.

He was asked:

Concerning what village headmen and neighborhood chiefs consume: is it lawful or not?

He replied:

If a headman wrongs people, whatever he takes from them unjustly is unlawful. Whatever belongs to him or has been acquired through a lawful means is permissible. If a neighborhood chief receives a reasonable fee for keeping watch and does not transgress against people, his fee is lawful.