An Nahl, 103 Ayah
16:103
وَلَقَدۡ نَعۡلَمُ أَنَّهُمۡ يَقُولُونَ إِنَّمَا يُعَلِّمُهُۥ بَشَرٞۗ لِّسَانُ ٱلَّذِي يُلۡحِدُونَ إِلَيۡهِ أَعۡجَمِيّٞ وَهَٰذَا لِسَانٌ عَرَبِيّٞ مُّبِينٌ ١٠٣
Wa Laqad Na`lamu 'Annahum Yaqūlūna 'Innamā Yu`allimuhu Basharun ۗ Lisānu Al-Ladhī Yulĥidūna 'Ilayhi 'A`jamīyun Wa Hadhā Lisānun `Arabīyun Mubīnun
And We certainly know that they say, "It is only a human being who teaches the Prophet." The tongue of the one they refer to is foreign, and this Qur'an is [in] a clear Arabic language.