Man Lā Yaḥḍuruh al-Faqīh
Hadith 1975164 - وَ رَوَى اَلْحَسَنُ بْنُ مَحْبُوبٍ عَنْ عَبْدِ اَللَّهِ بْنِ سِنَانٍ وَ اِبْنِ بُكَيْرٍ عَنْ أَبِي عَبْدِ اَللَّهِ عَلَيْهِ اَلسَّلاَمُ قَالَ: سُئِلَ عَنِ اَلْمُؤْمِنِ يَقْتُلُ اَلْمُؤْمِنَ مُتَعَمِّداً لَهُ تَوْبَةٌ فَقَالَ "إِنْ كَانَ قَتَلَهُ لِإِيمَانِهِ فَلاَ تَوْبَةَ لَهُ وَ إِنْ كَانَ قَتَلَهُ لِغَضَبٍ أَوْ لِسَبَبِ شَيْءٍ مِنْ أَمْرِ اَلدُّنْيَا فَإِنَّ تَوْبَتَهُ أَنْ يُقَادَ مِنْهُ وَ إِنْ لَمْ يَكُنْ عَلِمَ بِهِ أَحَدٌ اِنْطَلَقَ إِلَى أَوْلِيَاءِ اَلْمَقْتُولِ فَأَقَرَّ عِنْدَهُمْ بِقَتْلِ صَاحِبِهِمْ فَإِنْ عَفَوْا عَنْهُ فَلَمْ يَقْتُلُوهُ أَعْطَاهُمْ اَلدِّيَةَ وَ أَعْتَقَ نَسَمَةً وَ صَامَ "شَهْرَيْنِ مُتَتٰابِعَيْنِ"- وَ أَطْعَمَ سِتِّينَ مِسْكِيناً تَوْبَةً إِلَى اَللَّهِ عَزَّ وَ جَلَّ".
Hadith.5164 - Al-Hasan ibn Mahbub narrated from Abdullah ibn Sinan and Ibn Bukayr from Abu Abdullah (as), who was asked about a believer who intentionally kills another believer - does he have repentance?
Imam (as) said: "If he killed him because of his faith, then there is no repentance for him.
But if he killed him out of anger or due to some worldly reason, then his repentance is that retribution be taken from him.
If no one knows about it, he should go to the family of the murdered person and confess to them that he killed their relative. If they forgive him and do not kill him, he must give them the blood money (diyyah), free a slave, fast for two consecutive months, and feed sixty needy people as repentance to Allah (swt), the Almighty and Majestic."