Is money earned from a savings account, to which usurious interest is added, lawful or unlawful? And does it become lawful if the usurious interest is removed from it?

Saving money in a savings account is impermissible because it is a loan with a stipulated interest. Therefore, the questioner's sister is only entitled to the principal. As for the interest, it is unlawful and must be disposed of by spending it on charitable causes, acts of righteousness, and for the benefit of Muslims. It is sufficient for her to know the amount of the usurious interest and disburse it from her lawful money. She must withdraw the money from the bank or post office because depositing money in a savings account is usury.