Indeed...
Indeed, Ka'b Al-Ahbar was a real person; many companions knew him because he resided in Medina and was looked upon with high prestige by the second and the third Caliphs. He narrated many stories, claiming that they were from the contents of the Old Testament. Many famous companions, such as Abu Hurayrah, Abdullah Ibn 'Umar, Abdullah Ibn Amr Ibn Al-’As, and Mu'awiyah Ibn Abi Sufyan reported his stories. Ka'b was with 'Umar Ibn Al-Khattab when 'Umar entered Jerusalem.
This rabbi reported many strange tales, the contents of which testify for their own lack of authenticity. One such tale is the following: A companion named Qays Ibn Kharshah Al-Qaysi reported that Ka'b Al-Ahbar said: "Every event that has taken place or will take place, on any foot of the earth, is written in the Tawrat (Old Testament), which Allah revealed to His Prophet Moses.
(Ibn Abd al-Barr, Al-Isti'ab, part 3, page 1287) Such a report should arouse the attention of the reader, because it states that which is inconceivable. The earth contains billions of square miles, and each mile contains millions of cubic feet, and each part of the earth may become a place of thousands of events from the time of Moses until the Day of Judgement. Yet, Ka'b al-Ahbar claimed that all these events are recorded in the Old Testament.
The parts of the Old Testament which were dictated or written by Moses do not come to 400 pages. Recording all the events of the world, between the time of Moses and the Day of Judgement, may take millions of pages. If we take all that was written in the Old Testament, including the books which are attributed to the Prophets after Moses and before Jesus, it does not amount to more than 900 pages. How could this small number of pages contain the record of billions of events.
In fact, if only the events of death and birth alone were recorded from the time of Moses until the Day of Judgement, they would reach astronomical figures. Furthermore, the pages of the Old Testament do not record future events. All they contain are some past events which took place during or before the time of the biblical Prophets.
Considering all these aspects, the claim of Ka'b Al-Ahbar that the Old Testament contains records of what had happened and what will happen until the Day of Judgement belies itself. Ka'b Al-Ahbar Counts The Days Of The Caliph 'Umar This international Rabbi was able to deceive many companions through his trickery.