Yusuf - 12:2

إِنَّا أَنزَلْنَاهُ قُرْآنًا عَرَبِيًّا لَّعَلَّكُمْ تَعْقِلُونَ
[12:2]
Surely We have revealed it-- an Arabic Quran-- that you may understand.
We have sent it down as an Arabic Qur'an, in order that ye may learn wisdom.
Lo! We have revealed it, a Lecture in Arabic, that ye may understand.