10:15
وَإِذَا تُتْلَىٰ عَلَيْهِمْ ءَايَاتُنَا بَيِّنَـٰتٍ ۙ قَالَ ٱلَّذِينَ لَا يَرْجُونَ لِقَآءَنَا ٱئْتِ بِقُرْءَانٍ غَيْرِ هَـٰذَآ أَوْ بَدِّلْهُ ۚ قُلْ مَا يَكُونُ لِىٓ أَنْ أُبَدِّلَهُۥ مِن تِلْقَآئِ نَفْسِىٓ ۖ إِنْ أَتَّبِعُ إِلَّا مَا يُوحَىٰٓ إِلَىَّ ۖ إِنِّىٓ أَخَافُ إِنْ عَصَيْتُ رَبِّى عَذَابَ يَوْمٍ عَظِيمٍ
And when Our verses are recited to them as clear evidences, those who do not expect the meeting with Us say, "Bring us a Qur'an other than this or change it." Say, [O Muhammad], "It is not for me to change it on my own accord. I only follow what is revealed to me. Indeed I fear, if I should disobey my Lord, the punishment of a tremendous Day."
Context in Surah Yunus
Nearby ayahs help place verse 10:15 in sequence and meaning.
وَلَقَدْ أَهْلَكْنَا ٱلْقُرُونَ مِن قَبْلِكُمْ لَمَّا ظَلَمُوا۟ ۙ وَجَآءَتْهُمْ رُسُلُهُم بِٱلْبَيِّنَـٰتِ وَمَا كَانُوا۟ لِيُؤْمِنُوا۟ ۚ كَذَٰلِكَ نَجْزِى ٱلْقَوْمَ ٱلْمُجْرِمِينَ
And We had already destroyed generations before you when they wronged, and their messengers had come to them with clear proofs, but they were not to believe. Thus do We recompense the criminal people
ثُمَّ جَعَلْنَـٰكُمْ خَلَـٰٓئِفَ فِى ٱلْأَرْضِ مِنۢ بَعْدِهِمْ لِنَنظُرَ كَيْفَ تَعْمَلُونَ
Then We made you successors in the land after them so that We may observe how you will do.
قُل لَّوْ شَآءَ ٱللَّهُ مَا تَلَوْتُهُۥ عَلَيْكُمْ وَلَآ أَدْرَىٰكُم بِهِۦ ۖ فَقَدْ لَبِثْتُ فِيكُمْ عُمُرًا مِّن قَبْلِهِۦٓ ۚ أَفَلَا تَعْقِلُونَ
Say, "If Allah had willed, I would not have recited it to you, nor would He have made it known to you, for I had remained among you a lifetime before it. Then will you not reason?"
فَمَنْ أَظْلَمُ مِمَّنِ ٱفْتَرَىٰ عَلَى ٱللَّهِ كَذِبًا أَوْ كَذَّبَ بِـَٔايَـٰتِهِۦٓ ۚ إِنَّهُۥ لَا يُفْلِحُ ٱلْمُجْرِمُونَ
So who is more unjust than he who invents a lie about Allah or denies His signs? Indeed, the criminals will not succeed