Would the eldest son's refusal to accept his share of the inheritance, which his maternal uncle gave to his mother for a pittance, be considered disobedience to his mother after her death and a transgression against God's law?

Inheritance enters the ownership of the heir by force, even if he refuses to receive it. It remains his property and is inherited from him if he dies. An adult of sound judgment may voluntarily relinquish his share to whomever he wishes, as long as this does not harm a mandatory maintenance obligation he has. Males are not permitted to deprive females of their share or compel them to accept compensation for it. Females have the right to take the matter to the Sharia court if this occurs.