A man came to the Prophet (may Allah's peace and blessings be upon him) and said: O Messenger of Allah, what if a man comes to me wanting to take my money? He said: You are not required to submit to him and give him your money. He said: What if he fights with me? He said: You are permitted to fight him. He said: What if he kills me? He said: Then you would be a martyr. He said: What if I kill him? He said: He deserves to be punished in Hellfire on the Day of Judgment.