Thank you for being with me in getting deeper into this issue. I did not deny that Ka’b maligned Mohammad. I can even admit it was a treachery. My objective in the study – was that so-called treachery warrant an assassination? You said yes, which is fine. But what treachery did he commit? Satirical poem!
The bottom line – the only recorded evidence that Ka’b was killed was because of the poems he composed. One was satirizing Mohammad personally and the other slighting Muslim women.
Ka’b did not kill any of Mohammad’s men.
He did not lift up any weapon.
He did not raise an army.
He did not mount any military attack on Mohammad.
His crime was coming out with the poems, an indirect dig at Mohammad. He was unhappy because Mohammad put to death the notables of Mekkah, naturally criticism would be leveled against him by Ka’b.
Treason is an overkill to justify his killing. The obvious reason Muslim apologists need to use this route is if they want to avoid the poems being the reason for the killing. That seems to me is their course.
Bukhari vol.5 book 59 no.360 p.248 is the longest hadith on the assassination of Ka’b bin Al-Ashraf. “(369) Narrated Jabin bin ‘Abdullah : Allah’s Apostle said, ‘Who is willing to kill Ka’b bin Al-Ashraf who has hurt Allah and His Apostle?’ Thereupon Muhammad bin Maslama got up saying, ‘O Allah’s Apostle! Would you like that I kill him?’ The Prophet said, ‘Yes.’ Muhammad bin Maslama said, ‘Then allow me to say a (false) thing (i.e. to deceive Ka’b).’ The Prophet said, ‘You may say it.’ Then Muhammad bin Maslama went to Ka’b and said, ‘That man (i.e. Muhammad demands Sadaqa (i.e. Zakat) from us, and he has troubled us, and I have come to borrow something from you.’ On that, Ka’b said, ‘By Allah, you will get tired of him!’ Muhammad bin Maslama said, ‘Now as we have followed him, we do not want to leave him unless and until we see how his end is going to be. Now we want you to lend us a camel load or two of food.’ (Some differences between narrators about a camel load or two.) Ka’b said, ‘Yes, (I will lend you), but you should mortgage something to me.’ Muhammad bin Maslama and his companion said, ‘What do you want?’ Ka’b replied, ‘Mortgage your women to me.’ They said, ‘How can we mortgage our women to you and you are the most handsome of the Arabs?’ Ka’b said, ‘Then mortgage your sons to me.’ They said, ‘How can we mortgage our sons to you? Later they would be abused by the peoples’ saying that so-and-so has been mortgaged for a camel load of food. That would cause us great disgrace, but we will mortgage our arms [weapons] to you.’
Muhammad bin Maslama and his companion promised Ka’b that Muhammad would return to him. He came to Ka’b at night along with Ka’b’s foster brother, Abu Na’ila. Ka’b invited them to come into his fort, and then he went down to them. His wife asked him, ‘Where are you going at this time?’ Ka’b replied, ‘None but Muhammad bin Maslama and my (foster) brother Abu Na’ila have come.’ His wife said, ‘I hear a voice as if dropping blood.’ Ka’b said, ‘They are none but my brother Muhammad bin Maslama and my foster brother Abu Na’ila. A generous man should respond to a call at night even if invited to be killed.” Muhammad bin Maslama went with two men. (Some sub-narrators mention the men as Abu ‘Abs bin Jabr, Al-Harith bin Aus and ‘Abbad bin Bishr.) So Muhammad bin Maslama went in together with two men, and said to them, ‘When Ka’b comes, I will touch his hair and smell it, and when you see that I have got hold of his head, strike him. I will let you smell his head.’ Ka’b bin Al-Ashraf came down to them, wrapped in his clothes, and diffusing perfume. Muhammad bin Maslama said, ‘I have never smelt a better scent than this.’ K’ab replied, ‘I have got the best Arab women who know how to use the high class of perfume.’ Muhammad bin Maslama requested Ka’b ‘Wall you allow me to smell our head?’ Ka’b said, ‘Yes.’ Muhammad smelt it and made his companions smell it as well. Then he requested Ka’b again, ‘Will you let me (smell your head)?’ Ka’b said, ‘Yes.’ When Muhammad got a strong hold of him, he said (to his companions), ‘Get at him!’ So they killed him and went to the Prophet and informed him." Bukhari vol.5 book 59 no.369 p.248-250
Some study found that there is nothing in early Muslim literature that says Ka’b did any of these things (below). Without any evidence, perhaps the English translator made up this defense of Mohammed. Mohammed (truly or falsely) believed he said or did something, but the footnote might be inventing charges to justify the assassination.
In the translation of the Sahih Muslim hadiths, footnote 2269 p.990 says, “Ka’b b. Ashraf was a Jew belonging to the tribe of Nadir and thus he was pledged to honour the treaty made between the Muslims and Banu Nadir, but he never honoured that pledge. He conspired against the life of the Holy Prophet (may peace be upon him), helped the Meccans against the Muslims, sang obscene songs and amatory sonnets with a view to defaming the Muslim women. The victory of Badr mortified him and he shifted to Mecca and stirred up the Quraish to avenge their heroes of Badr. All these acts of his were directly contravening the covenant in which he had entered along with the members of his tribe. Who can tolerate such an immoral conspirator who breaks the treaty, conspires against the Head of the Islamic State, and the State itself, and drags the honour of the women into the mire and pollutes the pious atmosphere of the Islamic society with immoral songs? All these crimes were enough to take his life.”