What is the ruling on one who swore an oath of triple divorce upon his mother that she must bring her inheritance, otherwise his wife would be forbidden to him and he would not speak to her until death, but she was unable to bring it due to her brothers' refusal?

We advise you to be dutiful to your mother and to accompany her with kindness. It is not considered kindness to cut ties with her or abandon her, so repent to Allah for that. As for your specific question, it holds many possibilities related to the type of oath (triple divorce, prohibiting the wife), the timing of the prohibition, your intention behind bringing your mother the inheritance (absolute, immediate, or unintentional), and whether there was a reason for the oath that has now ceased or not. Also, your intention behind the prohibition could be a divorce, a ẓihār, an oath, or no intention at all. This matter is complex, so we advise you to verbally consult scholars about it, or to write down exactly what you uttered, detailing your intention and the circumstances of the oath. Know that it is not permissible for you to cut ties with your mother, even if maintaining ties with her leads to the divorce of your wife or her prohibition.