Question:

According to Ibn Kathir, do Jewish sources creep into religious texts?

Answer:

Isma’il Ibn Umar Ibn Kathir writes:

فهذا الإسناد إلى هؤلاء الصحابة مشهور في تفسير السدي ويقع فيه إسرائيليات كثيرة، فلعل بعضها مدرج ليس من كلام الصحابة، أو أنهم أخذوا من بعض الكتب المتقدمة، والله أعلم. والحاكم يروي في مستدركه بهذا الإسناد بعينه أشياء ويقول على شرط البخاري 

“This chain of transmission to the Companions (Sahabah) is known in the Tafsir of As-Suddi and in it numerous Jewish stories are mentioned. Perhaps some of them have crept in and are not the words of the Companions (Sahabah) or were taken from some of the old books and God knows best and Al-Hakim An-Naisaburi in his Mustadrak narrates things with exactly the same chain and says that it fulfills the condition of Al-Bukhari.” [Tafsir Ibn Kathir, Volume 1 Page 230]