Mukhtasar Muslim

It is narrated from Sayyiduna Miqdad bin Aswad (may Allah be pleased with him) that he said: "O Messenger of Allah! If I confront a disbeliever, he fights with me and cuts off one of my hands with a sword, then takes shelter behind a tree and says, 'I have submitted to Allah,' should I kill him after he has said this?" The Prophet (peace and blessings be upon him) said, "Do not kill him." I said, "O Messenger of Allah! He has cut off my hand, then said this—should I kill him?" The Prophet (peace and blessings be upon him) said, "Do not kill him." (Even though you have suffered harm and injury from him.) "If you kill him, then his state will be like yours before you killed him, and your state will be like his before he said this statement."

´Sayyiduna Usama bin Zaid (may Allah be pleased with him) says` The Messenger of Allah (peace and blessings be upon him) sent us on a military expedition. In the morning, we fought with the Harqat, who are from Juhainah. Then I found a man who said "La ilaha illallah" (There is no god but Allah), but I killed him with a spear. After that, I felt doubt in my heart (that it was not right to kill him after he said La ilaha illallah). I related this to the Messenger of Allah (peace and blessings be upon him), so he said, "Did he say La ilaha illallah and you killed him?" I said, "O Messenger of Allah! He said it out of fear of the weapon." The Prophet (peace and blessings be upon him) said, "Did you cut open his heart so that you would know whether his heart had said the word or not?" (Meaning, how could you know the state of his heart?) Then the Prophet (peace and blessings be upon him) kept repeating this until I wished that I had embraced Islam that day (so that after accepting Islam, I would not have been involved in such a sin, because previous sins of disbelief are forgiven upon embracing Islam). Sayyiduna Sa'd bin Abi Waqqas (may Allah be pleased with him) said, "By Allah, I will never kill any Muslim until the one with two bellies, i.e., Usama, kills him." A man said, "Has Allah not said: 'And fight them until there is no more fitnah (polytheism, idol worship) and the religion is Allah's alone'?" So Sayyiduna Sa'd (may Allah be pleased with him) said, "We fought (the disbelievers) so that there would be no fitnah, and you and your companions fight so that there is fitnah."

Narrated from Safwan bin Muharriz that Sayyiduna Jundub bin Abdullah Bajali (may Allah be pleased with him) sent a message to As'as bin Salamah when the turmoil of Sayyiduna Abdullah bin Zubair (may Allah be pleased with him) occurred, saying: Gather some of your brothers so that I may speak to them. As'as sent word to the people, and when they gathered, Sayyiduna Jundub (may Allah be pleased with him) came, wearing a yellow burnous (the burnous is a cap that people used to wear in the early days of Islam). He said: Continue your conversation as you were. When it was Sayyiduna Jundub’s turn (meaning he had to speak), he removed the burnous from his head and said: I have come to you only with the intention of narrating to you a hadith of your Prophet. The Messenger of Allah (peace and blessings be upon him) sent a Muslim army against a group of polytheists, and they met (i.e., confronted each other on the battlefield). Among the polytheists was a man who would attack and kill any Muslim he wished. Eventually, a Muslim saw him in a state of heedlessness. And people told us (that) the Muslim was Sayyiduna Usamah bin Zaid (may Allah be pleased with him). When he raised his sword against him, the man said: La ilaha illallah (There is no god but Allah), but he killed him. Afterwards, a messenger came to the Messenger of Allah (peace and blessings be upon him) with glad tidings. The Prophet (peace and blessings be upon him) asked him about the situation, and he narrated everything, including the incident of that man. The Prophet (peace and blessings be upon him) called him and asked: Why did you kill him? Sayyiduna Usamah (may Allah be pleased with him) said: O Messenger of Allah! He caused much harm to the Muslims, killed so-and-so and so-and-so, and mentioned several people. Then, when I overpowered him and he saw the sword, he said: La ilaha illallah. The Messenger of Allah (peace and blessings be upon him) said: Did you kill him? He replied: Yes. The Prophet (peace and blessings be upon him) said: What will you answer to La ilaha illallah when it comes on the Day of Resurrection? He said: O Messenger of Allah! Pray for my forgiveness! The Prophet (peace and blessings be upon him) said: What will you answer to La ilaha illallah when it comes on the Day of Resurrection? Then the Prophet (peace and blessings be upon him) did not say anything more than this, and kept repeating: What will you answer to La ilaha illallah when it comes on the Day of Resurrection?