The Prophet's illiteracy as a miracle

وَمَا كُنتَ تَتْلُوا۟ مِن قَبْلِهِۦ مِن كِتَـٰبٍ وَلَا تَخُطُّهُۥ بِيَمِينِكَ ۖ إِذًا لَّٱرْتَابَ ٱلْمُبْطِلُونَ

And you did not recite before it any scripture, nor did you inscribe one with your right hand. Then [i.e., otherwise] the falsifiers would have had [cause for] doubt.