Ka'b ibn Asad (Arabic: كعب ابن اسعد) was the chief of the Qurayza, a Jewish tribe that lived in Medina until 627.
A tribesman, Al-Zabir ibn Bata, claimed that his face "was like a Chinese mirror, in which the girls of the tribe could see themselves", presumably meaning that Kaab had a youthful and innocent appearance.
However, Muhammad did not fall into the trap but announced: "If thou judgest, judge in equity, for Allah loveth those who deal fairly".
According to Ibn Ishaq, a Qurayza had slain some Nadir noblemen and wanted to pay only half the usual blood money.
[7] Ka'b was one of 13 Jewish leaders representing all three major tribes who came to Muhammad to make a formal declaration of their joint unbelief.
In February, the qibla, the direction of prayer, was changed from Jerusalem to Mecca[9][10] After the Battle of Badr, he expelled the Jewish Qaynuqa tribe from Medina after their conspiracies against the Muslims were discovered.
They agreed to accept the decision made by Sa'ad Bin Mu'az regarding them, who they hoped would treat them softly as he had alliance with them in the past.
Sa'ad Bin Mu'az applied the law of the Old Testament and he decided to slay all the men, enslave all the women and children, and take all the lands of the Jewish tribe.
"[13] In April 627 a confederacy of Arab tribes attacked Medina, led by the chief of Mecca, Abu Sufyan, and the exiled Huyayy ibn Akhtab.
According to Ibn Ishaq, A Muslim spy discovered Ka'b's intentions and managed to persuade him that the confederates were about to lift the siege and to abandon him to Muhammad.
Abu Sufyan complained in a list of various difficulties for his army, "The Qurayza tribe have broken their word to us and we have not received what we wanted from them.... Be off, for I am going!"
[19] People thought that there would be a form of leniency on the Qurayza Quarter since Sa'ad ibn Mu'az was a former ally of the tribe, but they refused to accept his appeals to keep your pledges with Muhammad, which they denied in arrogance and support from Huyayy.
[20] Sa'ad ibn Mu'az, who was wounded during the previous battle, then arrived with several men to come and pass judgement on the tribe.
[19] The Qurayza warriors were kept in the Najjar quarter, where Muhammad’s own kinsmen lived, and the Muslims went to the marketplace to dig trenches.