Surah An Najm Tafseer

ذَلِكَ مَبْلَغُهُم مِّنَ الْعِلْمِ

That is what they could reach of knowledge.

meaning, seeking this life and striving hard in its affairs is the best knowledge they have acquired. There is also the reported supplication:

اللْهُمَّ لَا تَجْعَلِ الدُّنْيَا أَكْبَرَ هَمِّنَا وَلَا مَبْلَغَ عِلْمِنَا

O Allah! Make not this life the greatest of our concerns, nor the best knowledge that we can attain.

Allah's statement,

إِنَّ رَبَّكَ هُوَ أَعْلَمُ بِمَن ضَلَّ عَن سَبِيلِهِ وَهُوَ أَعْلَمُ بِمَنِ اهْتَدَى

Verily, your Lord is He, Who knows best him who goes astray from His path, and He knows best him who receives guidance.

meaning, He is the Creator of all creatures and He knows whatever benefits His servants. Allah is the One Who guides whom He wills and misguides whom He wills, and all of this indicates His power, knowledge and wisdom. Certainly, He is Just and never legislates or decrees unjustly