Is it permissible for sons or grandsons to appropriate a portion of Waqf land for residential purposes without paying rent, in accordance with the endower's conditions which stipulate that the endowment is for his progeny and descendants, with the exclusion of daughters' daughters?

Matters pertaining to endowments (waqf) are referred to the Sharia Court to consider the endower's condition and enforce it. It is not permissible to build residential structures on endowed land or to appropriate a portion of it if the endowment was designated for cultivation, rental, or deriving benefit from its yield. The endower's condition must be adhered to, provided that the condition is permissible. Shaykh al-Islam Ibn Taymiyyah permitted changing the endower's condition to what is more beneficial, even if it varies with the changing times, such as allocating an endowment designated for jurists and Sufis to soldiers if people are in need of jihad.