وَلَقَدۡ نَعۡلَمُ أَنَّهُمۡ يَقُولُونَ إِنَّمَا يُعَلِّمُهُۥ بَشَرٞۗ لِّسَانُ ٱلَّذِي يُلۡحِدُونَ إِلَيۡهِ أَعۡجَمِيّٞ وَهَٰذَا لِسَانٌ عَرَبِيّٞ مُّبِينٌ

Wa laqad na'lamu annahum yaqooloona innamaa yu'allimuhoo bashar; lisaanul lazee yulhidoona ilaihi a'ja miyyunw wa haaza lisaanun 'Arabiyyum mubeen

We know indeed that they say, "It is a man that teaches him." The tongue of him they wickedly point to is notably foreign, while this is Arabic, pure and clear.

— Al-Nahl (ٱلنَّحْل), 16:103