firm in his religious commitment and counted among the eminent scholars.
He narrated from ʿUmar, Suhayb, and a number of others. Those who in turn reported from him include Abū Hurayrah, Muʿāwiyah, and Ibn ʿAbbās—an instance of a Companion transmitting from a Successor, something exceedingly rare. Others who related from him were Aslam, the freedman of ʿUmar; Tubayʿ al-Ḥimyarī, the son of Kaʿb’s wife; and Abū Salām al-Aswad. A number of the Successors—such as ʿAṭāʾ ibn Yasār and others—also narrated from him in mursal form.
He was well versed in the Jewish scriptures and, on the whole, had a discerning taste for separating the authentic from the spurious. His narrations are found in Sunan Abī Dāwūd, al-Tirmidhī, and al-Nasāʾī (1).
In later life he settled in Syria and would march on expeditions with the Companions. Khalid ibn Maʿdān related from Kaʿb al-Aḥbār that he said: “For me to weep out of awe…"
It has been abrogated, and God has granted us what is sounder, more beneficial, clearer, and more eloquent; to Him belong all praise and grace.
Al-Bukhari relates in his Sahih, 13/281–282 (Book of Holding Fast to the Quran and the Sunnah, chapter: “The Prophet said, ‘Do not ask the People of the Book about anything’”), through the chain of Humayd ibn Abd al-Rahman, that he heard Muawiya addressing a group of Quraysh in Medina when he performed the pilgrimage during his caliphate. Muawiya mentioned Kaʿb al-Ahbar and said: “He was one of the most truthful of those who transmit reports from the People of the Book, yet even so we would still catch him lying.”
What Kaʿb quotes from the ancient scriptures is not considered authoritative by any scholar. ʿUmar, for example, said to him—as recorded by Abu Zurʿa al-Dimashqi in his History, 1/544—“Either you abandon these reports, or I will banish you to the land of the apes.”
Not everything attributed to Kaʿb in later writings is genuine; fabricators after his time ascribed to him many statements he never uttered.
(1) Anyone who claims that al-Bukhari or Muslim narrated hadith on Kaʿb’s authority is mistaken. Neither of them includes a single isnad that goes back to him; his name appears in the two Sahih collections only incidentally. None of the early authorities explicitly declared Kaʿb reliable, even though some Companions praised his knowledge.