Is investing in a company that offers a fixed profit percentage but with a variable timeframe for project completion and profit distribution considered permissible (halal), knowing that the project involves building a commercial mall and selling it? And does the investor bear sin if the buyer utilizes the mall for impermissible (haram) activities?

For Mudarabah (definition) (profit-sharing) to be valid, three conditions must be met: that the investment field be permissible, that the capital not be guaranteed so that any loss is borne by the capital owner, and that both parties agree on a known percentage of the profit, not a fixed amount or a percentage of the capital. If the capital is guaranteed and the profit is a fixed percentage of the capital, then this is a usurious, prohibited loan. Thus, an institution that manages investments and guarantees the capital is engaged in a prohibited transaction, because taking money while guaranteeing it to its owner is, in reality, a loan. If, in addition, it involves managing the money to generate profit, it becomes a combination of a loan and a sale, which is forbidden.

As for leasing and selling shops: It is permissible to lease or sell them to someone who will use them for permissible purposes. However, it is not permissible to lease or sell them to someone who will use them for sinful purposes, such as a usurious bank or a place selling alcohol. If a shop is leased or sold to someone who is known or presumed to use it for permissible purposes, and then a reprehensible act is committed therein, the sin falls upon the tenant or buyer, and this does not affect the validity of the contract.