::The Interpreter of the Qur’an::
Ibn Jarir At-Tabari reported that ‘Abdullah bin Mas’ud said: “Yes, Ibn ‘Abbas is the interpreter of the Qur’an.”
This Hadith has an authentic chain of narrators. Ibn Mas’ud died in the 32nd year of Hijrah and ‘Abdullah bin ‘Abbas lived for 36 years after that. Hence, what do you think about the knowledge that Ibn ‘Abbas collected after Ibn Mas’ud?
Al-A’mash said that Abu Wa’il said: “Ali once appointed ‘Abdullah Ibn ‘Abbas to lead the Hajj season. Ibn ‘Abbas gave a speech to the people in which he read and explained Surat Al-Baqarah (according to another narration, Surat An-Nur) in such a way, that if the Romans, Turks and the Daylam heard him, they would have embraced Islam.”
[Tafsir Ibn Kathir, Introduction by Ibn Kathir. Quoting At-Tabari 1:81 and 1:90.]