I first found this verse while reading the context of a verse. I do not know if it's a feature of the Arabic language. Qur'an 2:74 (emphasis mine):
2:74 ثُمَّ قَسَتْ قُلُوبُكُم مِّنۢ بَعْدِ ذَٰلِكَ فَهِىَ كَٱلْحِجَارَةِ أَوْ أَشَدُّ قَسْوَةًۭ ۚ وَإِنَّ مِنَ ٱلْحِجَارَةِ لَمَا يَتَفَجَّرُ مِنْهُ ٱلْأَنْهَـٰرُ ۚ وَإِنَّ مِنْهَا لَمَا يَشَّقَّقُ فَيَخْرُجُ مِنْهُ ٱلْمَآءُ ۚ وَإِنَّ مِنْهَا لَمَا يَهْبِطُ مِنْ خَشْيَةِ ٱللَّهِ ۗ وَمَا ٱللَّهُ بِغَـٰفِلٍ عَمَّا تَعْمَلُونَ ٧٤
Then your hearts became hardened after that, being like stones or even harder. For indeed, there are stones from which rivers burst forth, and there are some of them that split open and water comes out, and there are some of them that fall down for fear of Allāh. And Allāh is not unaware of what you do. — Saheeh International
The word used is أَوْ which does mean "or". Why does it use or about "like stones or harder" even though ALLAH is all knowing, thus meaning that HE doesn't doubt about what is actually true?
how is this explained?