Q 16:101

And when We change a verse in place of another - and Allah knows best what He reveals - they (the disbelievers) say: "You (O Muhammad) are but a forger." Rather, most of them know not (101)Say (O Muhammad); "Ruh-ul-Qudus has brought it (the Qur'an) down from your Lord with truth." for the conviction of those who believe, and as a guide and good news for the Muslims (102) The Idolators' Accusation that the Prophet (ﷺ) was a Liar since some Ayat were abrogated, and the Refutation of their Claims Allah tells us of the weak minds of the idolators, and their lack of faith and conviction. He explains that it is impossible for them to have faith when He has decreed that they are doomed. When they saw that some rulings had been changed by being abrogated, they said to the Messenger of Allah ﷺ: إِنَّمَا أَنتَ مُفْتَرٍ (You are but a forger) meaning one who tells lies. But Allah is the Lord Who does whatever He wills, and rules as He wants. بَدَّلْنَا آيَةً مَّكَانَ آيَةٍ (And when We change a verse (of the Qur'an) in place of another) Mujahid said: this means, "We remove one and put another in its place." Qatadah said: this is like the Ayah: مَا نَنسَخْ مِنْ آيَةٍ أَوْ نُنسِهَا (Whatever verse We change [abrogate] or omit [the abrogated]...)" (2:106). Allah said, in response to them: قُلْ نَزَّلَهُ رُوحُ الْقُدُسِ (Say: "Ruh-ul-Qudus has brought it...") meaning, Jibril, مِن رَّبِّكَ بِالْحَقِّ (from your Lord with truth,) meaning, with truthfulness and justice لِيُثَبِّتَ الَّذِينَ آمَنُوا (for the conviction of those who believe,) so that they will believe what was revealed earlier and what was revealed later, and humble themselves towards Allah. وَهُدًى وَبُشْرَىٰ لِلْمُسْلِمِينَ (and as a guide and good news for the Muslims.) meaning He has made it a guide and good news to the Muslims who believe in Allah and His Messengers.