And We certainly know that they say, "It is only a human (16:103)

Almuntakhab Fi Tafsir Alquran Alkarim

And We do know what they say, thus: He -Muhammad- is being taught by a man who dictates to him the words he expresses to the people. But the man they refer to is foreign while the Quran is being revealed in plain Arabic literary form

Tafseer Tafheem-ul-Quran by Syed Abu-al-A'la Maududi

(16:103) We know very well what they say about you: "Surely a certain person teaches him. " *107 But the person to whom they allude speaks a foreign tongue, and this (Qur'an) is in plain Arabic.

And We certainly know that they say, "It is only a human meaning

*107) In this connection, traditions mention the names of several persons, one of whom (Jabar), according to the disbelievers of Makkah taught the Holy Prophet; however, one thing particularly noteworthy about all these persons is that they were non-Arab slaves. Whosoever he might be, the fact that he used to recite the Torah and the Gospel and had an acquaintance with the Holy Prophet, gave an opportunity to the disbelievers for spreading this false report that it was the particular slave who was the real author of the Holy Qur'an, but Muhammad (Allah's peace be upon him) presented it as the Word of God. This not only shows that his opponents were very impudent in spreading false accusations against the Holy Prophet but also that, in general, people are not just in judging the worth of their contemporaries. They were ill-treating like this that great personality who has had no parallel in history. Nevertheless, these people who had become blind in their opposition, preferred to attribute the authorship of the matchless Arabic Qur'an to a non-Arab slave who had a smattering of the Torah and the Gospel. Instead of accepting the claim of the Holy Prophet, who was an embodiment of truth, they attributed its authorship to an insignificant foreign slave.
 

And We certainly know that they say, "It is only a human meaning in Urdu

ہمیں معلوم ہے یہ لوگ تمہارے متعلق کہتے ہیں کہ اس شخص کو ایک آدمی سکھاتا پڑھاتا ہے حالانکہ ان کا اشارہ جس آدمی کی طرف ہے اس کی زبان عجمی ہے اور یہ صاف عربی زبان ہے