Ka’b al-Ahbarwho (died 32-34 H.) was ,according to Islamic teaching, a learned Muslim of Jewish, possibly rabbinic, origin and a specialist in Biblical lore. K’ab al-Ahbar was a friend and confidant of Umar and the Prophet’s wife, Aisha.

He was Jew from southern Arabia who lived at the time of Omar ibn al-Khattab, the second caliph (634–44), and Uthman ibn Affan, the third caliph (644–56). Kab was possibly a descendant of the Judaizing Himyarites. He converted to Islam during the reign of Omar. The designation al-Ahbar (plural of habr=a non-Muslim religious scholar) signifies that he was ranked among the scholars. Indeed, many sayings of the rabbis and words of the aggadah are mentioned in his name in Muslim literature, from which it can be deduced that he was familiar with the Oral Law. Kab was one of the followers of Omar when the latter entered Jerusalem, and upon his request he pointed out the site where the Temple had stood. According to tradition, the Christians had attempted to conceal it from the conquerors. When he revealed this site, Kab tried to persuade Omar to build the Mosque (of Omar) to the north of the Rock, so as to include the latter in the qibla (direction) to Mecca. But Omar repudiated this suggestion, which he considered inspired by Judaizing tendencies. He sternly rebuked Kab and assigned the qibla to the front of the Temple Mount (south of the Rock). A saying quoted in Kab's name by the geographer al-Hamadhani (BGA V, p. 97) testifies to his veneration of the Rock: "Allah told the Rock: thou art my Throne and from thee I ascended to Heaven..." According to Tabari and Ibn al-Athir, Kab remained with Omar until the latter was murdered. He warned Omar some days before the attack that he would die shortly. Kab was also present in the court of the third caliph. There he had some encounters with Abu Dharr, a Muslim pietist. Baladhuri says that Uthman once asked Kab if a ruler is permitted to take money from the treasury when he is in need and to pay it back later. Kab found nothing wrong in such an action. Abu Dharr therefore remarked: "You son of Jews want to teach us!" Similar anecdotes are told by Tabari and Masudi. These anecdotes (also the above story about the qibla) show that the attitude of the historians toward Kab was not congenial. He was seen as the prototype of Jewish opportunism. This was not the case with the authors of the "Legends of the Prophets," for whom he is considered a firsthand authority.