“The Messenger of Allah (may peace be upon him) said: Act against the polytheists, trim closely the moustache and grow beard” (Sahih Muslim, Book 2, Hadith 69).
“Then they surrendered, and the apostle confined them in Medina in the quarter of d. al-Harith, a woman of B. al-Najjar. Then the apostle went out to the market of Medina (which is still its market today) and dug trenches in it. Then he sent for them and struck off their heads in those trenches as they were brought out to him in batches. Among them was the enemy of Allah Huyayy b. Akhtab and Ka’b b. Asad their chief. There were 600 or 700 in all, though some put the figure as high as 800 or 900. As they were being taken out in batches to the apostle they asked Ka’b what he thought would be done with them. He replied, “Will you never understand? Don’t you see that the summoner never stops and those who are taken away do not return? By Allah it is death!” This went on until the apostle made an end of them” (Ibn Ishaq. The Life of Muhammad. Pakistan: Oxford University Press, 2004, p. 464).
“O you who believe, what (excuse) have you that when it is said to you, Go forth in Allah’s way, you should incline heavily to earth? Are you contented with this world’s life instead of the Hereafter? The provision of this world’s life is but little as compared with the Hereafter. If you do not go forth, He will punish you with a painful punishment, and bring in your place a people other than you, and you can do Him no harm.c And Allah is Powerful over all things ” (Maulana Muhammad Ali. The Holy Quran 9:38-39. Ahmadiyya Anjuman Lahore Publications, 2010. p. 239).
Some Zanadiqa (atheists) were brought to ‘Ali and he burnt them. The news of this event, reached Ibn ‘Abbas who said, “If I had been in his place, I would not have burnt them, as Allah’s Messenger forbade it, saying, ‘Do not punish anybody with Allah’s punishment (fire).’ I would have killed them according to the statement of Allah’s Messenger, ‘Whoever changed his Islamic religion, then kill him'” (Sahih Al-Bukhari, Book 88, Hadith 5).
“I intend that I should command a person to lead people in prayer, and then burn those persons who absent themselves from Jumu’a prayer in their houses” (Sahih Muslim, Book 5, Hadith 321).