The Surah takes its name from the phrase wad-in-naml which occurs in verse 18, implying that it is a Surah in which the story of An-Naml (the Ant) has been related.
The subject matter and the style bear full resemblance with the Surahs of the middle Makkan period and this is supported by traditions as well. According to Ibn Abbas and Jabir bin Zaid, "First the Surah Ash-Shu\`araa' was sent down, then the Surah An Naml and then Al-Qasas."
The Surah consists of two discourses, the first from the beginning of the Surah to the end of verse 58, and the second from verse 59 to the end of the Surah.
The theme of the first discourse is that only those people can benefit from the guidance of the Quran and become worthy of the good promises made in it, who accept the realities which this Book presents as the basic realities of the universe, and then follow up their belief with obedience and submission in their practical lives as well. But the greatest hindrance for man to follow this way is the denial of the Hereafter. For it makes him irresponsible, selfish and given to worldly life, which in turn makes it impossible for him to submit himself before God and to accept the moral restrictions on his lusts and desires. After this introduction three types of character have been presented.
The first type is characterized by Pharaoh and the chiefs of Thamud and the rebels of the people of Lot, who were all heedless of the accountability of the Hereafter and had consequently become the slaves of the world. These people did not believe even after seeing the miracles. Rather they turned against those who invited them to goodness and piety. They persisted in their evil ways which are held in abhorrence by every sensible person. They did not heed the admonition even until a moment before they were overtaken by the scourge of Allah.
The second type of character is of the Prophet Solomon (peace be upon him), who had been blessed by God with wealth and kingdom and grandeur to an extent undreamed of by the chiefs of the disbelievers of Makkah. But, since he regarded himself as answerable before God and had the feeling that whatever he had was only due to Allah's bounty, he had adopted the attitude of obedience before Him and there was no tinge of vanity in his character.
The third type is of the queen of Sheba, who ruled over a most wealthy and well known people in the history of Arabia. She possessed all those means of life, which could cause a person to become vain and conceited. Her wealth and possessions far exceeded the wealth and possessions of the Quraish. Then she professed shirk, which was not only an ancestral way of life with her, but she had to follow it in order to maintain her position as a ruler. Therefore, it was much more difficult for her to give up shirk and adopt the way of Tauhid than it could be for a common mushrik. But when the Truth became evident to her, nothing could stop her from accepting it. Her deviation was, in fact, due to her being born and brought up in a polytheistic environment and not because of her being a slave to her lusts and desires. Her conscience was not devoid of the sense of accountability before God.
In the second discourse, at the outset, attention has been drawn to some of the most glaring and visible realities of the universe, and the disbelievers of Makkah have been asked one question after the other to the effect : "Do these realities testify to the creed of shirk which you are following, or to the truth of Tauhid to which the Qur'an invites you?" After this the real malady of the disbelievers has been pointed out, saying, "The thing which has blinded them and made them insensitive to every glaring reality is their denial of the Hereafter. This same thing has rendered every matter and affair of life non-serious for them. For, when according to them, everything has to become dust ultimately, and the whole struggle of life is purposeless and without an object before it, the truth and falsehood are equal and alike. Therefore, the question whether one's system of life is based on the right or wrong foundations, becomes meaningless for him."
But the discourse, as outlined above, is not meant to dissuade the Prophet and the Muslims from calling the obdurate and heedless people to the way of Tauhid ; it is, in fact, intended to arouse them from their slumber. That is why in vv. 67-93 certain things have been said repeatedly in order to produce in the people a sense of the Hereafter, to warn them of the consequences of being heedless of it, and to convince them of its coining, like an eye witness of something, who convinces the other person of it, who has not seen it.
In conclusion, the real invitation of the Quran that is, the invitation to serve One Allah alone, has been presented in a concise but forceful manner, and the people warned that accepting it would be to their own advantage and rejecting it to their own disadvantage. For if they deferred their faith until they saw those Signs of God after the appearance of which they would be left with no choice but to believe and submit, they should bear in mind the fact that that would be the time of judgment and believing then would be of no avail.
Source: Sayyid Abul Ala Maududi - Tafhim al-Qur'an - The Meaning of the Quran