Is it permissible to invest a sum of money to supply electricity to commercial shops affiliated with a mosque, provided that a percentage of the shops' rent is given in exchange for this investment, and what would be that percentage and the duration of the investment if it is permissible?

If the shops are endowed for the mosque, then it is not permissible to dispose of them or invest in them except through the supervisor of the endowment (nazir al-waqf) or the Sharia judge. It is permissible for the supervisor of the endowment or the judge to agree with the questioner or others to supply electricity to these shops for a fixed sum or a percentage of the rent for a specified period, as long as this is in the interest of the endowment. There is no specific limit for this percentage or duration; what matters is the interest of the endowment. It is permissible to build and plant trees on endowment land if it is beneficial to it, and the opinions of jurists differ regarding the ownership of such buildings or plantings.