Caution: Translations of Quran and Ḥadīth may lead to possible misapplications and misinterpretations. This site is intended for students of sacred knowledge that are proficient in comprehending classical Arabic and have a strong foundation in Islamic sciences. Also note that religious injunctions rely on several aspects beyond what one may glean through reading individual aḥādīth.
Qurʾān Bukhārī Muslim Nasāʾī Abū Dāwūd Tirmidhī Ibn Mājah Mālik Aḥmad Dārimī Ḥākim Ibn Ḥibbān Ṭabarānī Nasāʾī's Kubrá Bayhaqī al-Luʾluʾ wa-al-Marjān Ibn Rajab's Fifty Riyāḍ al-Ṣāliḥīn Aḥmad's Zuhd Suyūṭī
quran:16:103 –

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.  

And verily (wa-laqad is for confirmation) We know that they say, ‘It is only a human that is teaching him, the Qur’ān’ — this was a Christian blacksmith whom the Prophet (s) used to frequent. God, exalted be He, says: The tongue, the language, of him to whom they refer, to whom they incline, ˹with the accusation˺ that he is ˹the one˺ teaching him, is foreign’; while this, Qur’ān, is ˹in˺ a clear Arabic tongue, one of lucidity and clarity: so how can a foreigner be teaching him?
القرآن:١٦:١٠٣ –

وَلَقَدْ نَعْلَمُ أَنَّهُمْ يَقُولُونَ إِنَّمَا يُعَلِّمُهُ بَشَرٌ ۗ لِسَانُ الَّذِي يُلْحِدُونَ إِلَيْهِ أَعْجَمِيٌّ وَهَٰذَا لِسَانٌ عَرَبِيٌّ مُبِينٌ  

{ولقد} للتحقيق {نعلم أنهم يقولون إنما يعلمه} القرآن {بشر} وهو قين نصراني كان النبي ﷺ يدخل عليه قال تعالى {لسان} لغة {الذي يلحدون} يميلون {إليه} أنه يعلمه {أعجمي وهذا} القرآن {لسان عربي مبين} ذو بيان وفصاحة فكيف يعلمه أعجمي.