Is it permissible for the children of a deceased woman, who did not inherit from her grandfather's endowment (waqf) designated for males only, to demand the nullification of this endowment to redistribute it in accordance with Islamic law, knowing that the value of the endowment is significant and the will is not accessible to them?

Favoring some children with an endowment (waqf) or a gift without a legitimate Shariah justification is impermissible and unjust. The Prophet, peace and blessings be upon him, called it an act of injustice (jawr). Some scholars hold the view that such a favoritism is valid if the endower dies before retracting it. Shariah courts can adjudicate this matter, as a judge can rule the favoritism null and void.