Is it permissible for a woman who has neither children nor parents to bequeath all her land to her sister's daughter, or to donate it for the construction of a mosque, or to make a will for her sister's daughter for a portion of the land, while she has a brother and the sons of deceased brothers? And how is this land to be divided?

It is not permissible for a woman to transfer all her land to her niece (her sister's daughter) with the intention of disinheriting her brother, who is an heir. This applies whether it is a gift during her lifetime or a bequest after her death. Such an act is a circumvention aimed at nullifying inheritance, which is forbidden. If it is a bequest exceeding one-third of the estate, it is not enforceable without the consent of the heirs. However, she may bequeath to her niece one-third or less of the inheritance, as her niece is not an heir. If the woman passes away leaving a brother and nephews (sons of her brother), the entire inheritance goes to the brother after settling debts and executing any valid bequests. It is permissible for her to donate the land to build a mosque during her lifetime, as an act of devotion to Allah, without the intention of disinheriting her brother, provided she leaves something for her heirs. If she makes it a bequest, it is only enforceable within the limit of one-third of the estate.