THE BANU QURAYZAH BREAK A TREATY:
When the Messenger(sallallahu alaiyhi wassallam) of Allah came to Madinah, he had a covenant drawn up between the Muhajirun and Ansar to which the Jews were also a party. The Jews were given freedom of religion and protection of life and property. They had reciprocal obligations. The clauses included: 'Each must help the other against anyone who attacks. They must seek mutual advice and consultation, and piety rather than wrongdoing. They are bound to help one another against any attack on Yathrib.
However Huyayy ibn Akhtab, the Jew who was leader of the Banu'n-Nadir, encouraged the Banu Qurayzah to break the treaty and to collaborate with the Quraysh although another leader, Ka'b ibn Asad al-Qurazi, had said, 'I have seen nothing but truthfulness and loyalty in Muhammad. But Ka'b ibn Asad broke his word and absolved himself of any promise made between himself and the Messenger(sallallahu alaiyhi wassallam) of Allah. When this news reached the Prophet, he sent Sa'd ibn Mu'adh (may Allah be pleased with him), leader of the Aws (allies of the Banu Qurayzah) and Sa'd ibn 'Ubadah, leader of the Khazraj, with some Ansar representatives for confirmation. They found the situation even worse than they had feared.
'Who is the Messenger(sallallahu alaiyhi wassallam) of Allah ? There is no treaty or agreement between us and Muhammad, 'the Banu Qurayzah alleged.
They were preparing to attack the Muslims, threatening to stab them in the back. That was harder to bear and more harmful than any onslaught on an open battlefield. It is referred to in the Qur'an: 'When they came against you from above you and from underneath you.'(33:10)
The situation was extremely perilous for the Muslims.
THE ADVANCE ON THE BANU QURAYZAH:
When the Messenger(sallallahu alaiyhi wassallam) of Allah and the Muslims left the ditch to return to Madinah they laid down their weapons. Jibril (AS) appeared and asked, 'Have you laid down your weapons, Messenger(sallallahu alaiyhi wassallam) of Allah!' 'Yes,' he answered.
'The angels have not yet laid down their weapons. Allah the Mighty and Exalted commands you to go to the Banu Qurayzah. I am also to go there to shake them.'
The Messenger(sallallahu alaiyhi wassallam) of Allah had it announced that:
'Whoever hears and obeys should not pray 'Asr before arriving at the Banu Qurayzah.'
He pitched camp and laid siege to the Banu Qurayzah for twenty-five days. By then they were so hard pressed that they surrendered, for Allah Ta'aala had cast terror into their hearts.
Although the Banu Qurayzah submitted to the judgement of the Messenger(sallallahu alaiyhi wassallam) of Allah, the leaders of the Aws interceded on their behalf. They maintained that the Banu Qurayzah were their allies against the Khazraj. The Messenger(sallallahu alaiyhi wassallam) of Allah said,
'Will you be satisfied, Aws, if one of your men gives judgement on them?'
'Yes,' they replied.
The Messenger(sallallahu alaiyhi wassallam) of Allah said, 'Sa'd ibn Mu'adh is the right man.'
When Sa'd was brought to him, the Aws people begged him, Abu Amr! Deal well with your friends. The Messenger(sallallahu alaiyhi wassallam) of Allah appointed you for that so that you could be good to them.'
When they persisted, he said, 'A time has come when Sa'd is beyond caring about the praise or blame of anyone. I judge that the men be killed and their property divided up and that their children and women be taken as slaves.'
The Messenger(sallallahu alaiyhi wassallam) of Allah said, 'You have given the judgement of Allah regarding them.'
The judgement conformed with the law of war laid down for the Children of Isra'il given in the Torah. Sa'd ibn Mu'adh's sentence was carried out on the Banu Qurayzah and the Muslims were made safe from any acts of treachery.
Sallam ibn Abi'l-Huqayq was one of the Jews who had formed the confederation against the Muslims. The Khazraj killed him at his house in Khaybar. The Aws had already killed Ka'b ibn al-Ashraf who had done his utmost to incite the Quraysh against the Muslims and to slander the Messenger(sallallahu alaiyhi wassallam) of Allah. Thus, the Muslims were saved from the leaders of enemy movements against Islam.