All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and messenger.
This view is adopted by the majority of the scholars. Al-Mughni, authored by Ibn Qudaamah reads: “In conclusion, the father is not to be killed on account of killing his son, and the grandfather is not to be killed for killing his grandson, regardless of how distant they are in generation or whether they are the grandchildren from the sons or the daughters. Among those from whom it was reported that the father is not killed due to killing his son, was ‘Umar ibn Al-Khattaab . This is also the view of Rabee’ah, Ath-Thawri, Al-Awzaa’i, Ash-Shaafi’i, Is-haaq and the scholars of the Hanafi school of jurisprudence. However, Ibn Naafi’, Ibn `Abd Al-Hakam and Ibn Al-Munthir said: “The father is to be killed for killing his son.” Maalik said: “If he kills him by throwing a sword at him and the like, he is not killed for killing his son in this manner, and if he slaughters him or kills him in a manner that undoubtedly suggests that the father had the intent to kill him without trying to discipline him first, then legal retribution should be applied to him. The mother in this regard is like the father. This is the correct view of our school of jurisprudence, and this is the view acted upon by those who consider that there is no legal retribution on the father [due to killing his son]. It was reported from Ahmad what indicates that he does not exempt the mother from legal retribution.” [End of quote]
Allaah Knows best.