Allah, the Exalted, said:
٤٩ - باب إجراء أحكام الناس على الظاهر وسرائرهم إلى الله تعالى
Allah, the Exalted, said:
And when the inviolable months1 have passed, then kill the polytheists wherever you find them and capture them and besiege them and sit in wait for them at every place of ambush. But if they should repent, establish prayer, and give zakāh, let them [go] on their way. Indeed, Allāh is Forgiving and Merciful.
On the authority of Ibn ʿUmar (may Allah be pleased with them both): that the Messenger of Allah ― peace and blessings be upon him ― said: “I have been commanded to fight the people until they testify that there is no deity except Allah and that Muhammad is the Messenger of Allah, and establish the prayer, and give the zakat. When they do that, they have protected their blood and their wealth from me, except by the right of Islam, and their reckoning is with Allah the Exalted.” Agreed upon.
On the authority of Abu ʿAbdullah Tariq ibn Ashyam (may Allah be pleased with him), he said: I heard the Messenger of Allah ― peace and blessings be upon him ― say: “Whoever says there is no deity except Allah, and disbelieves in what is worshipped besides Allah, his wealth and his blood become inviolable, and his reckoning is with Allah the Exalted.” Narrated by Muslim.
On the authority of Abu Maʿbad al-Miqdad ibn al-Aswad (may Allah be pleased with him), he said: I said to the Messenger of Allah ― peace and blessings be upon him: Tell me, if I meet a man from the disbelievers and we fight one another, and he strikes one of my hands with the sword and cuts it off, then takes refuge from me behind a tree and says: I have submitted to Allah ― should I kill him, O Messenger of Allah, after he has said it? He said: “Do not kill him.” So I said: O Messenger of Allah, he cut off one of my hands, then said that after he had cut it off? He said: “Do not kill him, for if you kill him he is in your position before you killed him, and you are in his position before he spoke the word he said.” Agreed upon. The meaning of “he is in your position” is: inviolable in blood, judged to be a Muslim. The meaning of “you are in his position” is: lawful in blood through retaliation for his heirs ― not that he is in his position in disbelief. And Allah knows best.
On the authority of Usama ibn Zayd (may Allah be pleased with them both), he said: The Messenger of Allah ― peace and blessings be upon him ― sent us to al-Huraqa of Juhayna. We came upon the people in the morning at their watering places, and a man of the Ansar and I caught up with a man of them. When we overtook him, he said: There is no deity except Allah. The Ansari held back from him, but I stabbed him with my spear until I killed him. When we came to Medina, that reached the Prophet ― peace and blessings be upon him ― and he said to me: “O Usama, did you kill him after he said: There is no deity except Allah?!” I said: O Messenger of Allah, he was only seeking shelter by it. He said: “Did you kill him after he said: There is no deity except Allah?!” He kept repeating it to me until I wished I had not embraced Islam before that day. Agreed upon. In another narration: The Messenger of Allah ― peace and blessings be upon him ― said: “Did he say: There is no deity except Allah, and you killed him?!” I said: O Messenger of Allah, he only said it out of fear of the weapon. He said: “Did you not then split open his heart so that you would know whether he said it or not?!” He kept repeating it until I wished I had embraced Islam only on that day. “Al-Huraqa” is with a damma on the unpointed ḥāʾ and a fatḥa on the rāʾ: a clan of Juhayna, the well-known tribe. And his saying “mutaʿawwidhan” means: taking shelter by it from being killed, not believing in it.
On the authority of Jundub ibn ʿAbdullah (may Allah be pleased with him): that the Messenger of Allah ― peace and blessings be upon him ― dispatched a force of Muslims to a people of the polytheists, and they met in battle. There was a man of the polytheists who, whenever he wished to make for a man of the Muslims, made for him and killed him; and a man of the Muslims sought his unawareness ― we used to say that it was Usama ibn Zayd. When he raised the sword over him, he said: There is no deity except Allah, but he killed him. The bearer of glad tidings came to the Messenger of Allah ― peace and blessings be upon him ― and he asked him, and the man informed him, until he told him the account of the man and how he had acted. So he summoned him and asked him, saying: “Why did you kill him?” He said: O Messenger of Allah, he had caused injury among the Muslims and killed so-and-so and so-and-so ― and he named a number of men to him ― and I attacked him, and when he saw the sword he said: There is no deity except Allah. The Messenger of Allah ― peace and blessings be upon him ― said: “Did you kill him?” He said: Yes. He said: “Then what will you do with ‘There is no deity except Allah’ when it comes on the Day of Resurrection?” He said: O Messenger of Allah, seek forgiveness for me. He said: “And what will you do with ‘There is no deity except Allah’ when it comes on the Day of Resurrection?” He did no more than to keep saying: “What will you do with ‘There is no deity except Allah’ when it comes on the Day of Resurrection.” Narrated by Muslim.
On the authority of ʿAbdullah ibn ʿUtba ibn Masʿud, he said: I heard ʿUmar ibn al-Khattab (may Allah be pleased with him) say: People used to be dealt with by revelation in the time of the Messenger of Allah ― peace and blessings be upon him ― but the revelation has now ceased, and we only judge you now by what is apparent to us of your deeds. So whoever shows us good, we grant him security and bring him near, and we have nothing to do with his inner self ― Allah will call him to account for his inner self; and whoever shows us evil, we do not feel safe from him and do not believe him, even if he says: My inner self is good. Narrated by al-Bukhari.