Is it permissible for a father who suffers from illnesses and is unable to earn a living, and has a small income that is insufficient for life's necessities and his children's education, to take the bank interest on his end-of-service gratuity as assistance, or is it considered forbidden usury? And what is the ruling on depositing it in Islamic transactional banks?

"End-of-service benefits must not be deposited into an interest-bearing account, as their returns are usurious (riba), and they must be withdrawn immediately. They can be deposited into an investment account at an Islamic bank if its transactions are Sharia (definition)-compliant. The holder of usurious interest may not benefit from it unless they are poor and in need, in which case they may take from it only what suffices their need. They may also give it as charity to themselves and their dependents if they are poor."