How can money inherited from the bank be purified from the suspicion of usury, given that the amount of the original capital is unknown?

In Egypt, the matter is straightforward, as the heirs' representative can go to the Central Bank or the bank where the deceased's money is deposited and obtain a detailed account statement for a small fee. This will allow them to ascertain the details of the usurious returns and distinguish them from the principal.

If this is not possible, then diligence must be exercised to ascertain the amount of the forbidden (haram) wealth so that all the usurious returns are disbursed, ensuring the purity of the remaining amount. If the source of the money is unknown—whether it is from a lawful (halal) or forbidden (haram) source—it is considered halal by scholarly consensus. However, if it is known to contain haram and there is doubt about its exact amount, the amount of the haram should be disbursed through diligent estimation.

Some contemporary scholars are of the view that a precautionary measure is to disburse half of the doubtful money. It is not permissible to keep funds in an interest-based bank after the death of the inheritor.