[Arabic has undergone evolution since the Qur’an was revealed. Trying to understand it through the Arabic that became prevalent a few centuries later or today will result in inaccuracies. It is of paramount importance to know that the original dialect is not extinct. It is very much alive and well in the Pre-Islamic and ‘Para-Islamic’ poetry and well preserved in some good dictionaries.]
We all know that for understaning of the Quran we always need Quraish Arabic of the time of the Exalted Prophet. And this is not possible except having good old Arabic dictionaries. It is usually said that "God only gurantees preservation of the text of the Quran and not other books".
My question is that does God also insure preservation of the language of the Quran (e.g. by preserving old dictionaries)?
Do verses 75:17-19 allude to this subject?