Judaism was already well established in Medina two centuries before Muhammad's birth. Although influential, the Jews did not rule the oasis. Rather, they were clients of two large Arab tribes there, the Khazraj and the Aws Allah, who protected them in return for feudal loyalty. Medina's Jews were expert jewelers, and weapons and armor makers. There were many Jewish clans-some records indicate more than twenty, of which three were prominent-the Banu Nadir, the Banu Qaynuqa, and the Banu Qurayza.
Various traditions uphold different views, and it is unclear whether Medina's Jewish clans were Arabized Jews or Arabs who practiced Jewish monotheism. Certainly they were Arabic speakers with Arab names. They followed the fundamental precepts of the Torah, though scholars question their familiarity with the Talmud and Jewish scholarship, and there is a suggestion in the Qur'an that they may have embraced unorthodox beliefs, such as considering the Prophet Ezra the son of God.
There were rabbis among the Jews of Medina, who appear in Muslim sources soon after Muhammad proclaimed himself a prophet. At that time the quizzical Meccans, knowing little about monotheism, are said to have consulted the Medinan rabbis, in an attempt to put Muhammad to the test. The rabbis posed three theological questions for the Meccans to ask Muhammad, asserting that they would know, by his answers, whether or not he spoke the truth. According to later reports, Muhammad replied to the rabbis' satisfaction, but the Meccans remained unconvinced.
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.
Yet Muhammad did not confuse the contentiousness of clan relations in the oasis with the religious message of Judaism. Passages in the Qur'an that warn Muslims not to make pacts with the Jews of Arabia emerge from these specific wartime situations. A larger spirit of respect, acceptance, and comradeship prevailed, as recorded in a late chapter of the Qur'an:
We sent down the Torah, in which there is guidance and light, by which the Prophets who surrendered to God's will provided judgments for the Jewish people. Also, the rabbis and doctors of the Law (did likewise), according to that portion of God's Book with which they were entrusted, and they became witnesses to it as well…. Whoever does not judge by what God has sent down (including the Torah), they are indeed unbelievers. (5:44)
Some individual Medinan Jews, including at least one rabbi, became Muslims. But generally, the Jews of Medina remained true to their faith. Theologically, they could not accept Muhammad as a messenger of God, since, in keeping with Jewish belief, they were waiting for a prophet to emerge from among their own people.
The exiled Banu Nadir and the Banu Qaynuqa removed to the prosperous northern oasis of Khaybar, and later pledged political loyalty to Muhammad. Other Jewish clans honored the pact they had signed and continued to live in peace in Medina long after it became the Muslim capital of Arabia.