What is the Islamic legal ruling on a person who kills his son or sons, and what is its evidence?

It is forbidden for a father to kill his son, even if for the purpose of discipline, due to the generality of texts prohibiting killing, such as the Almighty's saying: "And do not kill the soul which Allah has forbidden, except by right," and "And whoever kills a believer intentionally, his recompense is Hell."

If a father kills his son, he is not to be killed in retribution for it, based on the hadith: "A father is not killed for his son." However, blood money (diyya) becomes obligatory for him, as 'Umar ibn al-Khattab, may Allah be pleased with him, did with a man who killed his son. The father does not inherit from his killed son's wealth or from his blood money, due to the hadith: "There is nothing for the killer in inheritance."