As you know the Fatwā of the most of the jurists is that if a father intentionally kills his child, there will be no Qiṣāṣ (legal retribution) and execution and after the end of the imprisonment period, he will be released and will return to society and among the people as a murderer and criminal and there is no guarantee that such a person for whom the vileness of murder has not been eradicated, will not deliberately kill his other children or others again. Is the Fatwā of Ayatollah Haydari the same or different?

Wa ʿalykum al-Salām Ayatollah Haydari's Fatwā is that, as a first and foremost ruling, anyone who intentionally kills a human being their sentence is execution and Qiṣāṣ (legal retribution) and it does not matter whether the killer has a parent-child relationship with the victim or not. According to Ayatollah Haydari's basis in the Uṣūl al-Fiqh (principles of jurisprudence), it is not permissible to specificize al-ʿumumāt al-Qurʾniyah (the Qur'anic generalities) by al-Akhbār al-Aḥād (the single quoted narrations that are not Mutawātir) unless there are definite clues for that narration. It is necessary to mention that most of the contemporary Shiʿa jurists believe that to specificize al-ʿumumāt al-Qurʾniyah by al-Akhbār al-Aḥād is permissible, however, early Shiʿa jurists, including Sayyid Murtaḍa, Shaykh Ṭūsi and Muḥaqiq al-Ḥelli, did not consider it permissible. Based on this, the general verses such as: "وکتبنا علیهم فیها ان النفس بالنفس (مائدة 45)" And We ordained for them therein a life for a life And: "ولکم فی القصاص حیاة یا اولی الالباب لعلکم تتقون  (بقرة 179)" And there is for you in Qiṣāṣ (legal retribution) [saving of] life, O you [people] of understanding, that you may become righteous. will remain general and those contradicting narrations will be rejected. It must be added that from the point of view of Ayatollah Haydari, while the initial sentence for the murder of a child by the father is Qiṣāṣ (legal retribution), nevertheless, according to the law of each country and by competent legal institutions, each murder case must be investigated uniquely and separately to determine whether the killer in a premeditated murder had an acceptable and rational justification or not. In most cases, premeditated murders have no reasonable justification and the killer- even if he is the father- should be sentenced to retribution and execution unless in very rare cases where due to acceptable and reasonable justifications, the killer should not be sentenced to death. In other words, according to Ayatollah Haydari's method of Ijtihad and jurisprudence, prior to the issuance of any order, its al-Iṭlāq al-Afradi and al-Zamāni must be reviewed and proven, that is, it must be seen whether such a verdict is the same or different, in all cases and about all people and all times and different circumstances or not. Issuing rulings and Fatwās generally and regardless of various conditions and circumstances, is a sign of weakness and defect in the Ijtihadi attitude of a jurist.