What is the ruling on the interest from annual deposits whose rate was not predetermined, and what is the ruling on working in banks, dealing with them, or leasing real estate to them, and what is the expiation for working in banks if it is unlawful?

If the bank operates according to Islamic Sharia (definition) and invests the deposited funds through Sharia-compliant methods, then there is no harm in depositing money in it. However, if the bank does not adhere to Sharia rulings and engages in usurious activities, it is not permissible to deposit money in it or to take interest from it, even if the interest rate is not predetermined. Furthermore, it is not permissible to deal with such banks, work for them, or lease properties to them, because that falls under cooperating in sin and aggression. Whoever is afflicted by this must repent and cease doing so.