What is the ruling on investing in an investment account with an Islamic bank that provides a return based on Islamic Mudarabah, and is supervised by a Sharia supervisory board, given that the bank does not disclose the details of the Mudarabah or the profit ratio?

It is not a condition for the validity of the investment that the bank disclose the details of the Mudarabah (profit-sharing partnership); rather, what is necessary is that the Mudarabah conforms to Shariah guidelines, and that the profit ratio is known and clearly communicated.

This is the work of the Shariah Supervisory Board, and assessing the extent of its discipline and the bank's management adherence to its directives requires investigation, inquiry, and consulting scholars in the country where the bank is located.