Re: Banu Qurayza
Muhammad arrived in Medina in 622 believing the Jewish tribes would welcome him. Contrary to expectation, his relations with several of the Jewish tribes in Medina were uneasy almost from the start. This was probably largely a matter of local politics. Medina was not so much a city as a fractious agricultural settlement dotted by fortresses and strongholds, and all relations in the oasis were uneasy. In fact, Muhammad had been invited there to arbitrate a bloody civil war between the Khazraj and the Aws Allah, in which the Jewish clans, being their clients, were embroiled.
At Muhammad's insistence, Medina's pagan, Muslim and Jewish clans signed a pact to protect each other, but achieving this new social order was difficult. Certain individual pagans and recent Medinan converts to Islam tried to thwart the new arrangement in various ways, and some of the Jewish clans were uneasy with the threatened demise of the old alliances. At least three times in five years, Jewish leaders, uncomfortable with the changing political situation in Medina, went against Muhammad, hoping to restore the tense, sometimes bloody-but predictable-balance of power among the tribes.
According to most sources, individuals from among these clans plotted to take his life at least twice, and once they came within a bite of poisoning him. Two of the tribes--the Banu Nadir and the Banu Qaynuqa--were eventually exiled for falling short on their agreed upon commitments and for the consequent danger they posed to the nascent Muslim community.
The danger was great. During this period, the Meccans were actively trying to dislodge Muhammad militarily, twice marching large armies to Medina. Muhammad was nearly killed in the first engagement, on the plains of Uhud just outside of Medina. In their second and final military push against Medina, now known as the Battle of the Trench, the Meccans recruited allies from northwestern Arabia to join the fight, including the assistance of the two exiled Jewish tribes. In addition, they sent envoys to the largest Jewish tribe still in Medina, the Banu Qurayza, hoping to win their support. The Banu Qurayza's crucial location on the south side of Medina would allow the Meccans to attack Muhammad from two sides.
The Banu Qurayza were hesitant to join the Meccan alliance, but when a substantial Meccan army arrived, they agreed.
As a siege began, the Banu Qurayza nervously awaited further developments. Learning of their intention to defect and realizing the grave danger this posed, Muhammad initiated diplomatic efforts to keep the Banu Qurayza on his side. Little progress was made. In the third week of the siege, the Banu Qurayza signaled their readiness to act against Muhammad, although they demanded that the Meccans provide them with hostages first, to ensure that they wouldn't be abandoned to face Muhammad alone. Yet that is exactly what happened. The Meccans, nearing exhaustion themselves, refused to give the Banu Qurayza any hostages. Not long after, cold, heavy rains set in, and the Meccans gave up the fight and marched home, to the horror and dismay of the Banu Qurayza.
The Muslims now commenced a 25-day siege against the Banu Qurazya's fortress. Finally, both sides agreed to arbitration. A former ally of the Banu Qurayza, an Arab chief named Sa'd ibn Muadh, now a Muslim, was chosen as judge. Sa'd, one of the few casualties of battle, would soon die of his wounds. If the earlier tribal relations had been in force, he would have certainly spared the Banu Qurayza. His fellow chiefs urged him to pardon these former allies, but he refused. In his view, the Banu Qurayza had attacked the new social order and failed to honor their agreement to protect the town. He ruled that all the men should be killed. Muhammad accepted his judgment, and the next day, according to Muslim sources, 700 men of the Banu Qurayza were executed. Although Sa'd judged according to his own views, his ruling coincides with Deuteronomy 20:12-14.
Most scholars of this episode agree that neither party acted outside the bounds of normal relations in 7th century Arabia. The new order brought by Muhammad was viewed by many as a threat to the age-old system of tribal alliances, as it certainly proved to be. For the Banu Qurayza, the end of this system seemed to bring with it many risks. At the same time, the Muslims faced the threat of total extermination, and needed to send a message to all those groups in Medina that might try to betray their society in the future. It is doubtful that either party could have behaved differently under the circumstances.