When the Arabs stopped taking loans and paying interest on them...
When the Arabs stopped taking loans and paying interest on them, a rich source of revenue suddenly dried up for the Jews, and they bitterly resented this. They could now see that their grip on the economic life of Medina was beginning to loosen. 2. The Jews also realized that Islam was an enemy of the system of exploitation, and of the capitalist system. They began to see Islam as a threat to their economic interests. 3. The Jewish priests hated Muhammad as much as the Jewish money-lenders.
He had shown to the Jews how their priest followed deviant interpretations of their scriptures, and how they distorted their text. The priests, on their part, tried to convince their flocks that Muhammad did not have knowledge of their scriptures, and they tried to point out to them the “errors” in the Qur’an. The Jews also believed that they were safe only as long as the two Arab tribes of Medina, the Aus and the Khazraj, were fighting against each other.
Peace between the Aus and the Khazraj, they thought, would pose a threat to their survival in Arabia. For this reason, they were always fomenting trouble between them. Of the three Jewish tribes of Medina, the Banu Qainuka'a and the Banu Nadhir had already been expelled after the battles of Badr and Uhud respectively, and they had left with all their baggage, and herds of animals, and had resettled in Khyber. The third and the last tribe of the Jews in Medina was the Banu Qurayza.
According to the terms of the Charter of Medina, it was their duty to take an active part in defending the city during the siege of A.D. 627. But not only they did not contribute any men or materials during the siege but were actually caught conspiring with the enemy to compass the destruction of the Muslims. Some Jews even attacked a house in which many Muslim women and children had taken refuge as it was considered a safer place for them than their own houses.
If Amr ibn Abd Wudd had overcome the resistance of the Muslims, the Jews would have attacked them from the rear. Between the pagans of Makkah and the Jews of Medina, the Muslims would have been massacred. It was only the presence of mind of Muhammad and the daring of Ali that averted such a disaster. R.V.C.
Bodley The Jews were not at first inclined to listen to Abu Sofian's proposal (to attack Muslims from the rear), but after a while they compromised and agreed to betray the Moslems when the time seemed opportune.