Is a son's refusal to pay an unnecessary amount for his mother considered an act of disobedience, given that he meets her basic and essential needs, and that he has children who require educational expenses?

Filial piety is the greatest right after the worship of Allah Almighty. It is obligatory for the child to spend on their parents if they are in need. Based on the question, the mother does not need maintenance or housing, so the child is not legally obligated to give her money to buy housing she does not need and which will go to others. However, it is better for him to please his mother with what is not difficult for him, whether it is money or anything else, as the Prophet, peace and blessings be upon him, said: "The Lord's pleasure is in the parents' pleasure, and His displeasure is in their displeasure." Apartments are not owned through old rental contracts; they remain the property of their original owner, and thus the tenant is not permitted to sell them.