Is the money earned by an accountant who works for companies that deal with interest (riba) – even though his primary work is permissible (halal) – entirely forbidden (haram) or mixed? And does mixed money prevent prayers from being answered? And if it is mixed, is it permissible to estimate the forbidden portion based on the hours spent recording interest-based entries and then distribute it to Muslims?

It is permissible to work in companies engaged in legitimate work that involves some forbidden elements, provided that one avoids the forbidden actions. If the worker does not avoid the forbidden, then he must donate the portion of his salary that corresponds to this work. If the proportion of the forbidden can be estimated, he should donate it. Otherwise, he should make an earnest effort and donate what he believes will absolve him of responsibility, spending it on the welfare of Muslims or giving it to the poor and needy, along with repentance and abandoning the forbidden work. This is because consuming forbidden things is one of the impediments to the acceptance of supplication. As for an accountant recording usurious transactions, that requires further detail.