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.
The Saheeh International Quran Translation
وَلَقَدْ نَعْلَمُ أَنَّهُمْ يَقُولُونَ إِنَّمَا يُعَلِّمُهُۥ بَشَرٌ لِّسَانُ ٱلَّذِى يُلْحِدُونَ إِلَيْهِ أَعْجَمِىٌّ وَهَٰذَا لِسَانٌ عَرَبِىٌّ مُّبِينٌAnd 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.