Dual message: glad tidings and warning

فَإِنَّمَا يَسَّرْنَـٰهُ بِلِسَانِكَ لِتُبَشِّرَ بِهِ ٱلْمُتَّقِينَ وَتُنذِرَ بِهِۦ قَوْمًا لُّدًّا

So, [O Muḥammad], We have only made it [i.e., the Qur’ān] easy in your tongue [i.e., the Arabic language] that you may give good tidings thereby to the righteous and warn thereby a hostile people.