What is the expiation required from a deceased person who killed another in self-defense, and the family of the slain accepted the blood money, knowing that he did not fast for two months, or free a slave, or feed the poor, and what is incumbent upon his children?

A Muslim must defend himself, his family, and his property against anyone who assaults them. He is permitted to fight the aggressor if the aggression cannot be repelled except by killing, and there is no liability upon him at that time. If the person being assaulted is killed, he is a martyr. If the person being assaulted kills the aggressor, the aggressor is in the Fire. The person being assaulted is not permitted to initiate killing the aggressor unless easier means of repelling him have been exhausted, such as reminding him of Allah, and seeking help from others, unless he fears that the aggressor will initiate killing him. Retribution (qisas) is waived if it is proven that he killed in self-defense, either through clear evidence, or by the truthful admission of the victim's guardians, or by strong circumstantial evidence that indicates it.