وَمَا كُنْتَ تَتْلُو مِنْ قَبْلِهِ مِنْ كِتَابٍ وَلَا تَخُطُّهُ بِيَمِينِكَ إِذًا لَارْتَابَ الْمُبْطِلُونَ ﴿۴۸﴾ بَلْ هُوَ آيَاتٌ بَيِّنَاتٌ فِي صُدُورِ الَّذِينَ أُوتُوا الْعِلْمَ وَمَا يَجْحَدُ بِآيَاتِنَا إِلَّا الظَّالِمُونَ ﴿۴۹﴾ وَقَالُوا لَوْلَا أُنْزِلَ عَلَيْهِ آيَاتٌ مِنْ رَبِّهِ قُلْ إِنَّمَا الْآيَاتُ عِنْدَ اللَّهِ وَإِنَّمَا أَنَا نَذِيرٌ مُبِينٌ ﴿۵۰﴾

﴾48﴿ Wa maa kunta tatloo min qablihee min kitaabinw wa laa takhuttubhoo bi yameenika izal lartaabal mubtiloon
﴾49﴿ Bal huwa aayaatum baiyinaatun fee sudooril lazeena ootul 'ilm; wa maa yajhadu bi aayaatinaa illaz zaalimoon
﴾50﴿ Wa qaaloo law laaa unzila 'alaihi aayaatum mir Rabbihee qul innamal aayaatu 'indal laahi wa innamaaa ana nazeerum mubeen

﴾48﴿ You did not read any book before this (Quran), nor did you write it with your right hand, for then the followers of falsehood would have been in doubt
﴾49﴿ Rather, these are clear verses of the Quran in the hearts of those who have been given knowledge, and none deny Our signs except the unjust
﴾50﴿ And they say, Why are not miracles sent down to him from his Lord, Say, The control of miracles is only with Allah, and I am only a clear warner

[48] This is the second method—meaning that this Messenger does not read books nor can he write, so it is clear that he did not write this Book himself.
(bi-yamīnik) — this refers to common custom, indicating that writing is typically done with the right hand.
(idhan lartāba) — meaning, if this Prophet had been someone who wrote, then that would have given the deniers a reason (to doubt), but now there is absolutely no reason for doubt.
(al-mubṭilūn) — refers to those who oppose the truth by attempting to invalidate it through false doubts—either as intentional rejecters of the truth, or as followers of falsehood and false beliefs.
[49] This is the third method: the Qur’an is preserved in the hearts of the noble Companions and other scholars, and in the hearts of memorizers, so no one can alter or nullify it.
This is a unique feature of the Noble Qur’an—that it can be preserved not only by the prophets (peace be upon them), but also by members of the Ummah.
The previous scriptures were preserved only in the memories of the prophets (peace be upon them); the followers could not memorize them.
(ūtu al-‘ilm) — it becomes clear that, in the sight of Allah the Exalted, the people of the Qur’an are the true scholars.
Benefit: In verse (47), it says al-kāfirūn (the disbelievers), because it mentions disbelief in contrast to faith.
But in this verse, it mentions aẓ-ẓālimūn (the wrongdoers), because proofs of truthfulness have been mentioned, and even after that if someone still denies it, then he is stubborn and a wrongdoer.
[50] This is a rebuke against objecting to the truthfulness of the Messenger and the Qur’an, based on the assumption that bringing signs and miracles is within the Prophet’s control.
The first response is that miracles are solely under the authority and power of Allah the Exalted—the Prophet has no control over them.
This same point has also been mentioned earlier in Surah (38).