الكافي- ط الاسلامية, volume 7, page 276

A number of our companions, from Sahl Bin Ziyad and Muhammad Bin Yahya, from Ahmad Bin Muhammad, altogether from Ibn Mahboub from Abdullah Bin Sinan and Ibn Bakeyr, (It has been narrated) from Abu Abdullah asws , said, ‘He asws was asked about the Believer who kills the Believer deliberately, is there repentance for him? So he asws said: ‘If he killed him for his beliefs, so there is no repentance for him, and if had killed him due to anger, or for a reason for something from the affairs of the world, so his repentance is that he would be retaliated from it, and if he does not know of it, so he should go to the guardians of the killed one, so he confesses in their presence of the murder of their companions. So if they were to forgive from it, then he would not be killed, and he would give them the wergild, and emancipate a slave, and Fast for two moths consecutively, and feed sixty poor (people) as a repentance to Allah azwj Mighty and Majestic’.

Translation: HubeAli·Thaqalayn link·The Arabic above is the original.

A number of our companions, from Ahmad Bin Muhammad Bin Isa, from Al Husayn Bin Saeed, from Al Nazar Bin Suwed, from Abdullah Bin Sinan, (It has been narrated) from Abu Abdullah asws having been asked about a man who killed a Believer and he knew he was a Believer, besides that it was anger that carried him upon killing him. Is there repentance for him when he intends for that, or there is no repentance for him?’ So he asws said: ‘He would be retaliated with, and if he does not know, he should go to his (killed one’s) guardians, so he would let them know that he has killed him. So if they were to forgive him, he would give them the wergild, and emancipate a slave, and Fast for two months consecutively, and give charity upon sixty poor ones’.

Translation: HubeAli·Thaqalayn link·The Arabic above is the original.

Ali Bin Ibrahim, from his father, from Ibn Abu Umeyr, from Husayn Bin Ahmad Al Minqary, from Isa Al Zareyr who said, ‘I said to Abu Abdullah asws , ‘A man kills a man deliberately, what is his repentance?’. He asws said: ‘He should make himself available (to the guardians of the killed one)’. I said, ‘He is afraid that they might kill him’. He asws said: ‘So let him give them the wergild’. I said, ‘He is afraid that they would come to know (it was him) due to that’. He asws said: ‘So let him be secretive with the wergild, so let him make it as small packages, then place it during the Prayer timings (in their homes), so they can be with the wergild’.

Translation: HubeAli·Thaqalayn link·The Arabic above is the original.