"The Messenger of Allah ﷺ judged that the son is to suffer retaliation for [killing] his father, but the father is not to suffer retaliation for [killing] his son."

حَضَرْتُ رَسُولَ اللَّهِ ﷺ يُقِيدُ الأَبَ مِنِ ابْنِهِ وَلاَ يُقِيدُ الاِبْنَ مِنْ أَبِيهِ