do you know if either al-Tabari’s 10th century commentary on the Qur’an and the abridged version of the (14th c.) commentary by Ibn Kathir are available online anywhere? Could you direct me to the source if you are able to locate it online? I would appreciate it very much!
The commentary of ibn Kathir is not an abridged version of that one of Imam at-Tabari (even if the English wikipedia site seems to indicate this). They are two different books, but both follow the same method at-tafsir bi-l-M'athor التفسير بالمأثور (which means this commentary is based on sound narrations of interpretations -this means what sahaba have heard from the Prophet, what students of them have heard from them and so on, also based on interpretations of sahaba and their witness of some events if they have been approved by the Prophet to be good Quran interpreters like ibn 'Abbas- and without trying to interpret the meaning and don't quote what might be useless if there's no sound narration about it) . There's an abridged version (as I find it lacking a lot of the original text) of ibn Kathirs tafsir for example on this site or here.
I think it might be an English translation of the mukhtasar (summary) of ibn Kathir from as-Saboni (but it could be summarized by others also). At least it lacks some weak ahadith and the so called Israeliyat, which one would find in the books of ibn Kathir, at-Tabari and those who followed the same method.