he is a martyr.” This is because the Prophet (peace and blessings be upon him) was asked about a man who comes to another man intending to take his property. He said, “Do not give it to him.” The man asked, “What if he fights me?” He said, “Fight him.” He asked, “What if he kills me?” He said, “Then you are a martyr.” He asked, “What if I kill him?” He said, “He will be in the Fire.” (1) Thus, the Messenger (peace and blessings be upon him) said, “Fight him.” Accordingly, if he cannot be repelled except by killing him, then let him fight him. He incurs neither liability nor expiation.
As for its basis in the legal principles, it is because no liability attaches to what results from something permitted, and I am permitted to defend myself.
Question: Suppose that I fought him in defence of myself, my family, and my property, then his heirs demanded retaliation, saying, “You killed him, and we demand that you be put to death.” He replies, “I was defending myself.” They say, “Produce witnesses.” He says, “Had there been witnesses, he would not have attacked me.” They say, “You have nothing but a claim. You invited him into your house in order to kill him; therefore, we demand that you be put to death.” What is to be done?
Answer: The court rules that he is to be put to death, because the Prophet (peace and blessings be upon him) said: “If people were given what they claimed, some would claim the lives and property of others.” (2) If we were to accept such a claim, then anyone whose heart was filled with rancour towards another person could invite him into his house; when he came to the house, he could kill him and claim that the man had assaulted him and violated his inviolability. Since that is possible, though unlikely—