Must a father's will be carried out regarding an increase in a sum of money for one of the sons in the inheritance, and is there any sin upon him after the son bore the expenses of building the house, the expenses of the siblings, and paid the funeral expenses from the father's money, with the son's intention to divide the inheritance according to Islamic law and to perform Hajj on behalf of the parents and siblings?

A bequest to an heir is not enforceable except with the permission of the remaining heirs, due to the saying of the Prophet, peace and blessings be upon him: "Indeed, Allah has given every rightful person his right, and there is no bequest for an heir." The majority of jurists have held that it is permissible for an heir if the other heirs permit it after the testator's death. Therefore, your father's bequest to you is not enforceable unless the remaining heirs permit it; otherwise, it becomes part of the inheritance.