http://www.islam-watch.org/authors/65-khan/1257-assassinations-prophets-holy-tradition-takes-center-stage-in-the-muslim-world.html
Assassination, or secret killing, is the most dreaded weapon to demolish an opposition or to silence critics. Authoritarian, fascist and fanatic regimes have historical used assassination with great effectiveness. Today, from Tunisia to Bangladesh, assassinations by Islamist fanatics have been terrorizing their secular and progressive opponents.
In Islam, assassination was one of the violent tools that Prophet Muhammad used in its founding days. Here’s a brief list of the Prophet’s assassinations:
1) Abu Afak: He was famous poet, aged 120 years. He wrote a poem, condemning the Prophet’s murdering a man named al-Harith. Hearing of what Abu Afak has written, “The apostle said, ‘Who will deal with this rascal for me?’” And a disciple of Muhammad, named Salim b. Umayr, went forth and killed him at the dead of night. (Ibn Ishaq, The Life of Muhammad, p. 675)
2) Asma binte Marwan: She was poetess and mother of five children. When Prophet Muhammad assassinated the heavily-aged fellow poet Abu Afaq, Asma wrote a poem, condemning the tribes of Medina that had invited such a violent person and his murderous gang to their otherwise tranquil city. Ibn Ishaq writes, “When the apostle heard what she had said, he said, ‘Who will rid me of Marwan’s daughter?’” A disciple of Muhammad, named Umayr, went to her house that very night and killed her. In the morning when informed Muhammad of his killing of Asma, he said, ‘You have helped God and His apostle, O Umayr.’ When Umayr went to Asma house, she was sleeping with her breast-feeding baby on her cheast. He carefully removed the baby and plunged the sword through her chest so violently that it got stuck into the wooden bed below. (ibid, p. 675-76)
3) Kab bin Ashraf: Kab was a Jewish Prophet and critic of Muhammad. When Kab heard that a large number of the Quraish died in Muhammad’s aggressively plotted Battle of Bad’r, he reacted, “Is this true? Did Muhammad actually kill these, whom these two men mention? These are the nobles of the Arabs and kingly men; by God, if Muhammad has slain these people, it were better to be dead than alive” (Ibn Ishaq, p. 365). He felt so devastated at the death of so many Meccan noblemen that Hasan bin Thabit, Muhammad’s poet, wrote, “Does Ka’b weep for him again and again / And live in humiliation hearing nothing?….” A Muslim woman, ridiculing Ka’b, wrote: “This slave shows great concern / Weeping over the slain untiringly…”
Ka’b not only expressed grief at the slain Meccans, he also wrote a poem urging them to take revenge on Muhammad (ibid). When Muhammad heard about it, records Sahih Bukhari (5:369), “Allah’s messenger said, ‘Who is willing to kill Ka’b bin Al-Ashraf who has hurt Allah and His apostle?’ Thereupon Maslama got up saying, ‘O Allah’s messenger! Would you like that I kill him?’” Maslama also said that he will have to lie and deceive in order to kill Ka’b. Muhammad gave him permission to do that. Then on one night, Maslama lured Ka’b out of his house, saying he wanted to discuss something with him. When Ka’b, disregarding his wife’s concern, came out, two armed Muslim associates of Maslama, who were hiding nearby, came out and fell upon Ka’b and murdered him. (see also Ibn Ishaq, p. 367-68)