Haa Miim (Explained in Detail)
Surah 41 · Verse 44
And had We made it a Quran in a foreign (non Arabic) language, they would have said, “Why have not its signs* been explained in detail (in our Arabic language)? What! a (book in) foreign (language) and (the messenger and those addressed) Arabs?” Say, “For those who believe, it is a guide and a healing, and (for) those who do not believe, there is a heaviness in their ears and it is obscure to them, (it is as if) they are called from a far off place. (R 5) [* Statements]
The people who were directly addressed through the Quran were Arabs, therefore Arabic language was used, so that they could understand, implement and propagate the Quranic message which is a healing for the believers and obscure to the infidels.
