What is the ruling on a son taking money without the knowledge of his father, from whom he lives separately, while his siblings live with their father?

It is not permissible to take from a father's money without his permission, and the brothers residing with him does not make theft permissible. One must repent and return the money or seek absolution. If the father did not accommodate his son without a valid excuse, leaving his brothers to live with him, then he must be just among his children. However, if the lack of accommodation was due to the son's desire or the brothers' need, then there is no blame upon the father.