The following wiki extract demonstrates the possibility that the Muhammad's expulsion of Banu Qaynuqa and execution of Banu Qurayza to be a myth. Do authoritative Jewish historical records track or record this incident, if yes where it is recorded ?
In Muhammad and the Jews: A Re-examination, he questions the validity of the accepted accounts of Muhammad's expulsion of Banu Qaynuqa and execution of Banu Qurayza. The earliest surviving biography of Muhammad are recension of Ibn Ishaq's (d. 768) "Life of the Apostle of God". Ahmad argues that Muslim historians and Orientalists have failed to take into account that Ibn Ishaq's book, written some 120 to 130 years after Muhammad's death during the Abbasid Caliphate, was strongly influenced by the environment in which it was written. Ahmad accepts Ibn Ishaq as a sincere historian, but states that "a historian is very much part of his time. He cannot isolate himself from the climate of opinion in which he breathes" and argues that "Ibn Ishaq's view regarding Muhammad's relation with the Jews were strongly influenced by his own reaction to Jewish life under the Abbasids". Ahmad further argues that the account given by Ibn Ishaq cannot possibly be accurate, as, for example, states that the beheading and burial of 600-900 men would have been physically too colossal an undertaking for a small city like Medina,. He also writes that the corpses would have constituted an obvious menace to public health. To support his thesis, Ahmad also points to Jewish sources' silence about the alleged atrocity. Harold Kasimow, in a 1982 review for the Journal of the American Academy of Religion wrote: Dr. Ahmad has carefully considered all the early Islamic sources and the Jewish writings dealing with the period...Although I was not totally convinced by the evidence presented, there were moments during my reading when Dr. Ahmad did create doubt in my mind about the accuracy of the traditional history of the time. And that, after all, was his intent.
Also the story of Banu Quraiza in Ibn Ishaq on expulsion of Jews is conflicting with the following constition of Madina:
Article 20 Non-Muslim minorities (Jews) have the same right of life protection (like Muslims) A Jew, who obeys us( the state) shall enjoys the same right of life protection( as the believers do), so long as they (the believers) are not wronged by him. (the Jews), and he does not help (others) against them.
So does this account of expulsion and massacre of Jews bear any historical authenticity?