What is the expiation for injuring one's son in the eye with a hunting rifle shot in a moment of anger, and is blood money (Diyah) obligatory for that?

It is not permissible for a father to discipline his son by raising a weapon against him, for the Prophet, peace and blessings be upon him, forbade pointing a weapon at a Muslim, even if he were a brother.

While Islamic law permits the disciplining of children, it is bound by regulations, among which are that it must be for the purpose of discipline, not vengeance, and without excess or transgression. If the father oversteps these bounds and causes damage, he incurs sin and is liable.

Therefore, the father must repent to Allah and pay the blood money for his son's eye if it was damaged or its sight lost. The amount is half the blood money for a soul. However, the majority of scholars hold that retribution (qisas) is not applied to a parent for harming their child.