The Bee
وَلَقَدْ نَعْلَمُ أَنَّهُمْ يَقُولُونَ إِنَّمَا يُعَلِّمُهُۥ بَشَرٌ ۗ لِّسَانُ ٱلَّذِى يُلْحِدُونَ إِلَيْهِ أَعْجَمِىٌّ وَهَـٰذَا لِسَانٌ عَرَبِىٌّ مُّبِينٌ
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.
Nearby ayahs help place verse 16:103 in sequence and meaning.
وَإِذَا بَدَّلْنَآ ءَايَةً مَّكَانَ ءَايَةٍ ۙ وَٱللَّهُ أَعْلَمُ بِمَا يُنَزِّلُ قَالُوٓا۟ إِنَّمَآ أَنتَ مُفْتَرٍۭ ۚ بَلْ أَكْثَرُهُمْ لَا يَعْلَمُونَ
And when We substitute a verse in place of a verse - and Allah is most knowing of what He sends down - they say, "You, [O Muhammad], are but an inventor [of lies]." But most of them do not know.
قُلْ نَزَّلَهُۥ رُوحُ ٱلْقُدُسِ مِن رَّبِّكَ بِٱلْحَقِّ لِيُثَبِّتَ ٱلَّذِينَ ءَامَنُوا۟ وَهُدًى وَبُشْرَىٰ لِلْمُسْلِمِينَ
Say, [O Muhammad], "The Pure Spirit has brought it down from your Lord in truth to make firm those who believe and as guidance and good tidings to the Muslims."
إِنَّ ٱلَّذِينَ لَا يُؤْمِنُونَ بِـَٔايَـٰتِ ٱللَّهِ لَا يَهْدِيهِمُ ٱللَّهُ وَلَهُمْ عَذَابٌ أَلِيمٌ
Indeed, those who do not believe in the verses of Allah - Allah will not guide them, and for them is a painful punishment.
إِنَّمَا يَفْتَرِى ٱلْكَذِبَ ٱلَّذِينَ لَا يُؤْمِنُونَ بِـَٔايَـٰتِ ٱللَّهِ ۖ وَأُو۟لَـٰٓئِكَ هُمُ ٱلْكَـٰذِبُونَ
They only invent falsehood who do not believe in the verses of Allah, and it is those who are the liars.