You are mistaken.
What do you mean by "well grounded"?
See verse 3:7.
راسخون في العلم
Men of understanding of the meaning of the Quran. Who have been bestowed with knowledge by Allah, etc.
Right
I claim to be one as well. Pretty easy, huh?
Judging by the volumes he wrote, the sources he used, and the reputation he acquired, Ibn Kathir was clearly "well-grounded in knowledge", even of he didn't go around boasting about it like Sadiq.
If Sadigh was boasting that Allah made Him one of those who is well grounded in knowledge, one can say, Muhammad and other prophets were boasting around that they are a Messenger of God!!
It is not about boasting. It is about Allah choosing certain people to reveal His words, and certain people to explain and interpret His words. So, this was the case in Judaism. Moses revealed Book of God, then the prophets of Bani Israel explained and promoted the religion.
Likewise in Christianity, Jesus brought the new revelation, and then Allah also chose the Apostles to help. They became the teachers. As also confirmed in the Quran.
Likewise in Islam, Muhammad revealed the Book, and then those who were well-grounded in knowledge chosen by God to explain Quran.
just as a Prophet would tell, God chosen Him as Prophet, a well-grounded in Knowldeg would have done. So, did Sadigh.
ibni khatir did not claim., simply because he was not chosen by God.
Tell you what. You start your own thread and use Imam Sadiq as your preferred tafsir. Happy?
I am not biased towards anyone, Sadigh or anyone. I am discussing Islam Logically, according to its Sources.
Tell you what. You choose a verse from Quran which is difficult to understand, and bring a Tafseer from Ibni Khateer, or your own personal Tafseer. I will bring the explanation from those who claimed to be well-grounded in knowledge. And we compare their knowledge, and judge fairly. How's that?