An-Nahl · Ayah 103
وَلَقَدْ نَعْلَمُ أَنَّهُمْ يَقُولُونَ إِنَّمَا يُعَلِّمُهُۥ بَشَرٌ لِّسَانُ ٱلَّذِى يُلْحِدُونَ إِلَيْهِ أَعْجَمِىٌّ وَهَٰذَا لِسَانٌ عَرَبِىٌّ مُّبِينٌ
And We certainly know that they say, "It is only a human being who teaches him [i.e., the Prophet (ﷺ)]." The tongue of the one they refer to is foreign,[715] and this [recitation, i.e., Qur’ān] is [in] a clear Arabic language.
Translator's notes
[715] Having seen the Prophet (ﷺ) speaking with a foreign man on occasion, the Quraysh accused him of repeating the man's words.
Quran 16:103 (An-Nahl) · Saheeh International, Noor International Center (QuranEnc v1.1.2)