Is what the mother did—discriminating among her children in giving, and her financial dealings with her absent son, such as informing him of unreal prices for apartments or maintenance expenses, and giving him a small annual amount, then the brother demanding the difference in the price of the apartment he was supposed to own or the money he claims is rightfully his from her—permissible in Islamic law? Does this entail sin for the mother or the favored son? And what is the ruling on the dutiful, low-income son taking from his mother?

It is obligatory to be fair among children in giving gifts, and it is not permissible to prefer some over others, except to the extent of need. However, fairness is not obligatory in expenditures. What the mother did by gifting an apartment to one of her sons without his siblings is impermissible, and she must either equalize the gift or revoke it, unless all the siblings consent.

As for the apartment that the mother purchased for one of her sons through agency and then gave it to another son, this is impermissible. It belongs to the brother for whom it was purchased, and he has the right to claim it.

As for the money that the mother acquired from her son's funds without his consent, under the pretext of managing his affairs, it is not rightfully hers. The mother does not have the right to take her child's money if she is financially sufficient.

The brother has the right to demand that money from his mother, but it is preferable for him to waive his right to her. However, it is not permissible for him to abandon her or mistreat her. The questioner is advised to honor his mother and not accept favoritism in gifts.