What is the ruling on the remaining profits that were disbursed by the Islamic bank: Should they be calculated retroactively and given to the poor, or only from the date of knowing about the fatwa change? And what should be done with investment certificates: Should one wait until their term expires, or cancel them immediately and bear the loss?

Firstly: It is impermissible to invest in Islamic banks that place a portion of their funds in interest-bearing bonds or treasury bills, or that invest in organized tawarruq. This is because the bank acts on its own behalf primarily and on behalf of investors as an agent, thus the sin of prohibited transactions would affect them.

Secondly: Usurious interest that was collected before knowledge of its prohibition is lawful for the one who collected it, based on the Almighty's saying: "So whoever receives an admonition from his Lord and desists, he may have what has already passed." Al-Baqarah/275.

Thirdly: Investment in this bank must be stopped immediately, even if it results in financial loss, in order to flee from usurious dealings and in compliance with the Almighty's saying: "O you who have believed, fear Allah and give up what remains [due to you] of interest, if you should be believers. And if you do not, then be informed of a war from Allah and His Messenger. But if you repent, you may have your principal - [thus] you do no wrong, nor are you wronged." Al-Baqarah/278-279.