Muhammad bin Ka'b al-Qurazi and Uthman bin Yahudha, a man of Banu Amr bin Qurayzah, narrate from men of their people that people organized armies: a group of Banu al-Nadir and a group of Banu Wa'il; from Banu al-Nadir, Huyayy bin Akhtab, Kinanah bin al-Rabi' bin Abi al-Huqayq and Abu Ammar, and from Banu Wa'il (a clan of the Ansar from Aws Allah), Wahwah bin Amr and some men of their tribe. All of them together came to Quraysh, urging them to war against the Messenger of Allah (peace and blessings be upon him). Then he mentioned the coming of Abu Sufyan bin Harb and the armies. And (Ka'b) heard the voice of Huyayy bin Akhtab and shut the gate of the fortress. Huyayy said: "O Ka'b! Woe to you, open the gate, I want to come in to you." Ka'b said: "O Huyayy bin Akhtab! You are an ill-omened man. I have no need of you, nor of what you have brought. I have seen that Muhammad (peace and blessings be upon him) fulfils his promises; I have a treaty with him, so go back and leave me alone." Huyayy bin Akhtab said: "You have shut the gate (only because you fear) that I will eat porridge with you." He assured him of protection, so he opened the gate. When he went in to Ka'b, he said: "O Ka'b! I have brought you the glory of the age, Quraysh, with their leaders, and I have settled them at Rumah, and I have brought you the chiefs and leaders of Ghatafan and settled them beside Uhud. I have brought you a surging sea which nothing can hold back." Ka'b said: "You have brought me humiliation. Leave me and go away; I have no need of you or of what you invite me to." Huyayy bin Akhtab kept coaxing him until Ka'b accepted Huyayy's word, and Huyayy gave him a covenant and pledge that if Quraysh and Ghatafan left before killing Muhammad (peace and blessings be upon him), he would stay with him in the fortress, and whatever calamity and hardship befell him would befall him too. So Ka'b broke the covenant he had made with the Prophet (peace and blessings be upon him) and declared his disavowal.
Ibn Ishaq says: Asim bin Umar bin Qatadah says that when the news of Ka'b's breaking the covenant reached the Messenger of Allah (peace and blessings be upon him), he sent Sa'd bin Ubadah, Sa'd bin Mu'adh, Khawwat bin Jubayr and Abdullah bin Rawahah (may Allah be pleased with them) to verify the news, and the matter was just as the news had said.
Ibn Ishaq says: Asim bin Umar bin Qatadah narrates from a shaykh of Banu Qurayzah the reason for the acceptance of Islam of Tha'labah and Usayd, the sons of Sa'yah (may Allah be pleased with them both), and Asad bin Ubayd (may Allah be pleased with him), and the reason for their coming down from the fortress of Banu Qurayzah. That night, when he came out of the fortress and passed by Sayyiduna Muhammad bin Maslamah (may Allah be pleased with him), the guard of the Messenger of Allah (peace and blessings be upon him), he asked: "Who is it?" He said: "I am Amr bin Su'da." Amr had excused himself from joining Banu Qurayzah in their treachery and said: "I will never break faith with Muhammad (peace and blessings be upon him)." When Sayyiduna Muhammad bin Maslamah (may Allah be pleased with him) recognized him, he said: 'Allahumma la tahrimni 'atharat al-kiram' (O Allah, do not deprive me of (overlooking) the slips of noble people). Then he let him go, and he spent the night in the mosque of the Messenger of Allah (peace and blessings be upon him). Then it could not be known where he went. When the Messenger of Allah (peace and blessings be upon him) learned of it, he said: "Allah has saved him because of his faithfulness."
Musa bin Uqbah says concerning this story that Huyayy bin Akhtab remained with them with his ill omen, but Asad, Usayd and Tha'labah (may Allah be pleased with them) came to the Prophet (peace and blessings be upon him).
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الجزية / 18856