Is a son's abandonment of visiting his mother, due to her bias towards his older brother—the unjust one who seized the inheritance—and her hostility towards him, considered an act of disobedience to parents (ʿuqūq)?

"Filial piety towards the mother is obligatory, and the parents' differential treatment of their children leads to division and hatred. The mother's and brother's request to waive the inheritance is an injustice and an unlawful appropriation of wealth. Obedience to the mother in this matter is not obligatory; rather, they both should fear Allah. The mother's ill-treatment does not negate the obligation of filial piety and kindness towards her, but obedience to her in waiving the inheritance is not binding. Advising the brother about the obligation of prayer and the danger of abandoning it is necessary. Reminding the mother to save her son from abandoning prayer is more important than her eagerness to accumulate wealth for him, because abandoning prayer is disbelief, with which no good deeds will be beneficial."