Is it true that Tafsir Ibn Kathir contains many Isra'iliyyat?

Ibn Kathir's Tafsir (exegesis) is among the finest interpretations and is relied upon by scholars and common people alike. It contains some Isra'iliyyat (narrations from Jewish and Christian sources) which do not diminish its value, as the author often clarifies them by mentioning their chain of transmission (isnad) and commenting on them. The Tafsir is characterized by its simple language, its interpretation of the Qur'an by the Qur'an and the Sunnah, its mention of the sayings of the Salaf (pious predecessors), and its classification of hadiths. It has been said about it: "Nothing similar has been authored in its style."