The name, An-Nahl, of this Surah has been taken from v. 68. This is merely to distinguish it from other Surahs.
The following internal evidence shows that this Surah was revealed during the last Makkan stage of Prophethood:
v. 41 clearly shows that persecution had forced some Muslims to emigrate to Habash before the revelation of this Surah.
It is evident from v. 106 that at that time the persecution of the Muslims was at its height. Therefore a problem had arisen in regard to the utterance of a blasphemous word, without actual disbelief, under unbearable conditions. The problem was that if one did so how he should be treated.
vv. 112-114 clearly refer to the end of seven year famine that had struck Makkah some years after the appointment of the Holy Prophet as Allah's Messenger.
There is a reference to v. 116 of this Surah in VI: 145, and v. 118 of this Surah contains a reference to VI: 146. This is a proof that both these Surahs (VI and XVI) were sent down in the same period.
The general style of the Surah also supports the view that this was revealed during the last stage at Makkah.
All the topics of the Surah revolve round different aspects of the Message, ie., refutation of shirk, proof of Tauhid, and warning of the consequences of the rejection of and opposition and antagonism to the Message.
The very first verse gives direct and strict warning to those who were rejecting the Message outright, as if to say, "Allah's decision has already been made concerning your rejection of the Message. Why are you then clamoring for hastening it? Why don't you make use of the respite that is being given to you!" And this was exactly what the disbelievers of Makkah needed at the time of the revelation of this Surah. For they challenged the Holy Prophet over and over again: "Why don't you bring that scourge with which you have been threatening us! For we have not only rejected your Message but have been openly opposing it for a long time." Such a challenge had become a by-word with them, which they frequently repeated as a clear proof that Muhammad (Allah's peace be upon him) was not a true Prophet.
Immediately after this warning they have been admonished to give up shirk, for this false creed was the main obstacle in the way of the Message. Then the following topics come over and over again, one after the other:
Very convincing proofs of Tauhid and refutation of shirk have been based on the plain signs in the universe and in man's own self.
The objections of the disbelievers have been answered, their arguments refuted, their doubts removed and their false pretexts exposed.
Warnings have given of the consequences of persistence in false ways and antagonism to the Message.
The moral changes which the Message of the Holy Prophet aims to bring practically in human life have been presented briefly in an appealing manner. The mushriks have been told that belief in Allah, which they also professed, demanded that it should not be confined merely to lip service, but this creed should take a definite shape in moral and practical life.
The Holy Prophet and his companions have been comforted and told about the attitude they should adopt in the face of antagonism and persecution by the disbelievers.
Source: Sayyid Abul Ala Maududi - Tafhim al-Qur'an - The Meaning of the Quran
وَإِذَا رَأَى الَّذِينَ ظَلَمُوا الْعَذَابَ فَلَا يُخَفَّفُ عَنْهُمْ وَلَا هُمْ يُنظَرُونَ
وَإِذَا رَأَى الَّذِينَ أَشْرَكُوا شُرَكَاءَهُمْ قَالُوا رَبَّنَا هَٰؤُلَاءِ شُرَكَاؤُنَا الَّذِينَ كُنَّا نَدْعُو مِن دُونِكَ ۖ فَأَلْقَوْا إِلَيْهِمُ الْقَوْلَ إِنَّكُمْ لَكَاذِبُونَ
وَأَلْقَوْا إِلَى اللَّهِ يَوْمَئِذٍ السَّلَمَ ۖ وَضَلَّ عَنْهُم مَّا كَانُوا يَفْتَرُونَ
الَّذِينَ كَفَرُوا وَصَدُّوا عَن سَبِيلِ اللَّهِ زِدْنَاهُمْ عَذَابًا فَوْقَ الْعَذَابِ بِمَا كَانُوا يُفْسِدُونَ
وَيَوْمَ نَبْعَثُ فِي كُلِّ أُمَّةٍ شَهِيدًا عَلَيْهِم مِّنْ أَنفُسِهِمْ ۖ وَجِئْنَا بِكَ شَهِيدًا عَلَىٰ هَٰؤُلَاءِ ۚ وَنَزَّلْنَا عَلَيْكَ الْكِتَابَ تِبْيَانًا لِّكُلِّ شَيْءٍ وَهُدًى وَرَحْمَةً وَبُشْرَىٰ لِلْمُسْلِمِينَ
إِنَّ اللَّهَ يَأْمُرُ بِالْعَدْلِ وَالْإِحْسَانِ وَإِيتَاءِ ذِي الْقُرْبَىٰ وَيَنْهَىٰ عَنِ الْفَحْشَاءِ وَالْمُنكَرِ وَالْبَغْيِ ۚ يَعِظُكُمْ لَعَلَّكُمْ تَذَكَّرُونَ
وَأَوْفُوا بِعَهْدِ اللَّهِ إِذَا عَاهَدتُّمْ وَلَا تَنقُضُوا الْأَيْمَانَ بَعْدَ تَوْكِيدِهَا وَقَدْ جَعَلْتُمُ اللَّهَ عَلَيْكُمْ كَفِيلًا ۚ إِنَّ اللَّهَ يَعْلَمُ مَا تَفْعَلُونَ
وَلَا تَكُونُوا كَالَّتِي نَقَضَتْ غَزْلَهَا مِن بَعْدِ قُوَّةٍ أَنكَاثًا تَتَّخِذُونَ أَيْمَانَكُمْ دَخَلًا بَيْنَكُمْ أَن تَكُونَ أُمَّةٌ هِيَ أَرْبَىٰ مِنْ أُمَّةٍ ۚ إِنَّمَا يَبْلُوكُمُ اللَّهُ بِهِ ۚ وَلَيُبَيِّنَنَّ لَكُمْ يَوْمَ الْقِيَامَةِ مَا كُنتُمْ فِيهِ تَخْتَلِفُونَ
وَلَوْ شَاءَ اللَّهُ لَجَعَلَكُمْ أُمَّةً وَاحِدَةً وَلَٰكِن يُضِلُّ مَن يَشَاءُ وَيَهْدِي مَن يَشَاءُ ۚ وَلَتُسْأَلُنَّ عَمَّا كُنتُمْ تَعْمَلُونَ
وَلَا تَتَّخِذُوا أَيْمَانَكُمْ دَخَلًا بَيْنَكُمْ فَتَزِلَّ قَدَمٌ بَعْدَ ثُبُوتِهَا وَتَذُوقُوا السُّوءَ بِمَا صَدَدتُّمْ عَن سَبِيلِ اللَّهِ ۖ وَلَكُمْ عَذَابٌ عَظِيمٌ