The Banu Nadir, one of the three Jewish tribes in Madina and living in fortresses half-a-day’s distance from the city, possessed vast date gardens and were mostly occupied with agriculture. They had established a position of superiority in relation to the other Jewish tribes. For this reason, in cases of bloodshed, if someone was killed from the Banu Nadir, full blood money was paid, while only half was paid if a member of the Banu Qurayza was killed. This inequality with respect to the payment of blood money was later eradicated upon the Banu Qurayza’s appeal to Prophet Muhammad to abolish the custom.
After the Emigration, the Banu Nadir participated in the Madina Constitution as an ally of the Aws tribe. While not displaying a hostile attitude to the Muslims initially, they began openly showing hostility and aggression following the Battle of Badr and with the expulsion of the Banu Qaynuqa from the city. Their famous poet Ka’b ibn Ashraf, in particular, with his persuasive poetic skill and forceful rhetoric, satirized the Prophet and his Companions, went personally to Makka so as to recite elegies for the slain at Badr and rouse feelings of revenge within Abu Sufyan and the other polytheists, thus inciting the Makkans against the Muslims; he spent all his wealth to this end. Disturbed by his increasingly antagonistic and blatant actions against Islam, the Prophet cautioned him to put an end to this situation. Thereupon, by means of a plan which Muhammad ibn Maslama and a few others implemented, Ka’b ibn Ashraf – who did not hesitate to openly insult the sacred values of the Muslims at every opportunity – was killed (3 Rabi` al-Awwal/September 642). During the Battle of Uhud, the Banu Nadir Jews went to the military headquarters of the Makkan polytheists and provoked them against the Muslims. In addition, they occasionally wanted to engage in conflict with the Muslims and even made several attempts to assassinate Prophet Muhammad. Notwithstanding the Prophet’s warning them to abide by the terms of the treaty, his appeals were left unanswered.
In order to avenge the murder of his friends, the sole survivor of the Bi'r Al-Mauna massacre, ‘Amr ibn Umayya, killed two members of the Banu Amir ibn Sa'sa' in their sleep, on his return to Madina. However ‘Amr was unaware that these two individuals had become Muslim and had received assurance of protection from the Prophet. The Prophet was extremely saddened by the death of these people he had taken under his protection and declared that ‘Amr would pay the blood money for the two he inadvertently killed. As per the conditions of the Madina Constitution, the Prophet went to the Banu Nadir to ask them to share in the blood money, taking Abu Bakr, ‘Umar and ‘Ali with him. While the Banu Nadir welcomed them, they simultaneously tried to kill them by releasing a boulder from the roof under which they sat. Becoming aware of the situation, the Prophet took his Companions and left, returning to the city. It is also reported that the Banu Nadir made other plans to assassinate the Prophet, based on proposals they received from the Quraysh. With the Banu Nadir’s violation of the terms of the Madina Constitution, the Prophet sent word to them, asking them to leave the city within ten days. While the Banu Nadir had begun preparations to leave, 'Abd Allah ibn Ubayy dissuaded them, assuring them of his help. As such, besieging them, the Prophet invited them to come to an understanding (4 Rabi` al-Awwal). At first putting up a resistance, an ensuing fifteen day siege led the Jews to later consent to leaving the city, with their women and children, as well as a convoy of 600 camels loaded with their possessions. Some of them settled in Khaybar, while others settled in Syria.