Abbas - Tanwîr al-Miqbâs min Tafsîr Ibn ‘Abbâs
(And when We put a revelation) when We send Gabriel with an abrogating verse (in place of (another) revelation) in place of another abrogated verse, (and Allah knoweth best what He revealeth) and Allah knows the probity of that with which He commands His servants, (they say) the disbelievers of Mecca say: (Lo! thou art but inventing) from yourself, O Muhammad. (Most of them know not) that Allah commands His servants with that which is good for them.
And when We exchange a verse in place of a [different] verse, by abrogating it and revealing another, for the welfare of [God’s] servants — and God knows best what He reveals — they say, that is, the disbelievers [say] to the Prophet (s): ‘You are just a fabricator’, a liar, making it up yourself. Nay, most of them do not know, the true nature of the Qur’ān and the benefit [to God’s servants] of abrogation.
The Idolators' Accusation that the Prophet was a Liar since some Ayat were abrogated, and the Refutation of their Claim
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 :
إِنَّمَآ 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.
بَدَّلْنَآ ءَايَةً مَّكَانَ ءَايَةٍ
(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 ءَايَةٍ 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,
مِّن رَّبِّكَ بِالْحَقِّ
(from your Lord with truth, ) meaning, with truthfulness and justice
لِيُثَبِّتَ الَّذِينَ ءَامَنُواْ
(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 وَبُشْرَى 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.
Maududi - Sayyid Abul Ala Maududi - Tafhim al-Qur'an
This may also mean, "To send down one Commandment to elaborate upon the other, for the Commandments were sent down piecemeal in the Qur'an". For instance, the Commandments about "prohibition" and fornication were sent down gradually one after the other during several years. But We hesitate to accept this interpretation because An-Nahl is a Makki Surah and to the best of our information there is no instance to show that Commandments were sent down piecemeal at Makkah. Therefore, we prefer the other interpretation. The Qur'an has added details of one theme and explained the same with different kinds of illustrations at different places. Likewise it has related a story in different words at different places and presented its different aspects and details at other places. It has put forward one argument at one place to prove a theme and another at another place to prove the same theme. It has related one theme concisely at one place and in detail at the other. That is what the disbelievers of Makkah put forward as proof that Muhammad (Allah's peace be upon him) forged the Qur'an himself. They argued like this: "Had the Qur'an been the Word of Allah it would have related in full one thing at one place, for Allah's knowledge is not defective that He should have to think out gradually the details of a theme and to give different versions to explain the same thing. In contrast to this, the knowledge of a human being is defective. A man has to think out gradually as has been done in the case of the Qur'an which is a clear proof that you have forged it yourself."
The Holy Spirit': `fibril'. Instead of using the name of the Angel who brought Revelation, his title has been deliberately mentioned to warn the disbelievers that the 'Holy Spirit' who brought Revelation, is free from human frailties. He is neither dishonest that he should add something to or take away something from the Message he brought, nor is he a liar and forger that he should invent and state something in the name of Allah. Nor does he suffer from any human lust that he should practice a deceit. He is wholly pure and holy and conveys the Word of Allah intact.
That is, "The fact that Allah sends down His Message piecemeal does not mean that Allah's knowledge and wisdom are defective as you consider because of your folly. Allah sends His Revelations gradually because human intelligence and capacity to grasp are limited and defective which do not let him understand the whole theme at one and the same time and make it firm in his mind. Therefore, Allah in His wisdom conveyed His Revelation piecemeal through the Holy Spirit. He sends a theme gradually and gives its details by and by and uses different methods and.ways to make it plain to human beings so that they might grasp it according to their abilities and capabilities and become firm in their faith and knowledge.
The second practical wisdom of sending down the Qur'an piecemeal was that those Believers, who obediently followed it, should get necessary instructions for the propagation of Islam and the solution of other problems of life at the time when they were actually needed. It is obvious that if those instructions had been sent down before time and at one and the same time they would not have been useful.
The third practical wisdom of not sending down the Qur'an as a whole at one and the same time was to give good tidings and encouragement to the obedient servants who were suffering from persecution and encountering great obstacles because they needed it over and over again. That is why they were assured of ultimate success time and again to fill them with hope to carry on their mission.
(And when We put a revelation in place of (another) revelation…) [16:101-102]. This verse was revealed when the idolaters said: “Muhammad is mocking his Companions; one day he commands them to do something and the next day he forbids them from doing it, or brings instead something which is easier. He is nothing but a calumniator who says things of his own invention”, and so Allah, exalted is He, revealed this verse and the verse after it.