Is a son's causing his father's death by heart attack following an argument considered "manslaughter" (qatl al-khata') necessitating diyah (blood money) and kaffarah (expiation)?

Righteousness towards parents is an obligation, and being undutiful to them is one of the gravest major sins. Quarrelling with one's father and raising one's voice at him is a forbidden act of undutifulness. If one of the disputants suffers harm due to the dispute, and the other party knew that his opponent was prone to anger and affected by disputes, and intentionally quarrelled with him intending to cause him harm, then he is sinful. As for the issue of diyah (blood money) and kaffarah (expiation) in this case, there is no textual evidence for it unless it is imposed on the guarantor of the 'ain (evil eye caster), and this applies only to someone known to be an 'ain. As for the disputant, it cannot be definitively stated that he was the cause of the injury. It appears that there is no diyah or kaffarah due from him, according to Islamic law, especially if he did not intend harm, because he did not directly commit or cause the act, and what happened was due to something specific to the injured person. A person's liability is not engaged except with certainty. If the dispute or quarrel is over a legitimate right, there is no liability.