The Qur'aan was revealed at a certain time and in reference, in many cases, to a certain people or incident. It is sometimes easy for the reader to become complacent and to think of the Qur'aan in terms of referring just to something that happened, something bygone. He thereby closes his eyes unconsciously to the fact that the Qur'aan was not revealed only for a specific era or for a specific people. Instead it is the guidance for all of mankind until the Day of Judgement. It contains lessons that transcend the constraints of time and place. The reader must open his eyes and realise that the Qur'aan, although it refers to specific events, is laying down lessons and principles that are valid for all times and places.
Instead of thinking only about the event referred to, it is must more important for the reader to think about how the Quranic lesson is being manifested in front of his own eyes or is to be applied in his times.
This is not meant to downplay the importance of the science of asbaab an-nuzool (the study of the events leading up to a specific revelation). In many cases, the actual meaning or proper intent of a particular verse cannot be fully understood without looking to the verse's asbaab an-nuzool. But that does not mean that the verse itself or its ruling or lesson is restricted to only that occasion or only to those individuals to whom it was originally referring. If that were the case, then perhaps much of the Qur'aan would have no validity today. This important point is why scholars agree upon the maxim: the ruling is determined by the generality of the text and not by the particularity of the occasion of the ruling.
That the text of the Qur'aan was not to be confined by time and place was something well known to the scholars of tafseer throughout the ages. Whenever they turned to the Qur'aan, they found guidance for their own place and time because they realised that the lessons and rulings of the Qur'aan were not to be restricted to the time of the Companions رضي الله عنهم of the Prophet صلى الله عليه وسلم. This was clearly reflected in their commentaries of the Qur'aan. Salaahud-Deen Al-Khaalidi notes,
"Each and every generation of Muslims found in the text of the Qur'aan a discussion of what they were passing through and what would improve their lives as if the Qur'aan was being revealed at that moment in particular. Every one of the commentators of the Qur'aan started from the texts of the Qur'aan to develop and train his people and make their situation better. And from every commentary on the Qur'aan one can derive the level of culture and civilisation, customs, social life, level of belief and behaviour for the period in which the commentator lived. That commentary was a recording of the civilisation and history of that period. That was only the case because the texts of the Qur'aan were applicable to the time and place of the commentator and were directed to the people around him." 
Allaah سبحانه و تعالى states,
The dreams of the Prophets عليهم الصلاة والسلام were all true - which was a valuable support to the veracity of their message. Whether they were sleeping or awake, Shaytaan was not allowed to make them envision falsehood.
Sa'eed Ibn Jubayr رحمه الله reported that Ibn 'Abbaas رضي الله عنهما said: "The Prophets' dreams are part of revelation." 
Imaam Ahmad رحمه الله said: "The dreams of the Prophets عليهم الصلاة والسلام were part of revelation. Only ignorant individuals would belittle dreams and claim that they have no consequence." 
Dreams are, therefore, included in the meaning of the aayah:
The correct belief in tawheed (Islamic monotheism) does not mean that one simply recognises that there is a God or Creator. It goes beyond that to having the proper beliefs about that Creator and submitting to that Creator and God in all realms of life, either as an individual in his worship and behaviour or as a society.
Imaam Ibn Abil-'Izz al-Hanafi رحمه الله said: "Most of the soorahs in the Qur'aan are concerned with the two types of tawheed ; in fact, everysoorah in the Qur'aan [is concerned with tawheed]. The Qur'aan either reports about Allaah's Names and Attributes سبحانه و تعالى. This is the tawheedthat one must have knowledge about and that is reported. Or the Qur'aan calls to His worship, associating no partner with Him [in that worship] and abandoning any other idol other than Him. This is the tawheed of intention and will. Or the Qur'aan orders, prohibits or commands [His] obedience. These are essential aspects of tawheed and part of its completeness. Or the Qur'aan reports about how [Allaah سبحانه و تعالى] honours the people [who adhere to] tawheed and what He does for them in this world and what He graciously bestows upon them in the Hereafter. That is the reward for [adhering to] tawheed. Or [the Qur'aan] reports about the polytheists and how He treats them in this world and what kind of punishment that will receive in the end. That is the punishment for those who abandon the aspects of tawheed." 
Sayyid Qutb رحمه الله echoed that statement when he wrote: "Defining the real uloohiyyah  and clarifying its particular aspects of Lordship, Sustainer and Ruler, and defining uboodiyyah  and its limits that must not be trespassed, and going from all of that to mankind worshipping their true Lord, and recognising that Lordship, Sustaining and Ruling belong only to Him..  This is the main topic of the entire Qur'aan.. And what is beyond that is simply an explanation of what this great truth [tawheed] implies and requires in the life of humans, in every respect." 
There is no question that guiding the creation to the understanding and implications of Allaah's Oneness سبحانه و تعالى and Uniqueness (tawheed) is the overriding purpose of the Qur'aan. It is part of the nature of a human to want to know Allaah سبحانه و تعالى, his Lord and Creator. It is the Qur'aan that eloquently tells the human about his Lord such that he will then recognise the signs of his Lord, appreciate His actions and know His attributes. 
Through these teachings found in the Qur'aan, the human will increase his love and adoration for his Lord. He will worship Him with greater intensity and love and he will be a more devoted servant to Him. 
Through Allaah's سبحانه و تعالى clear description of His complete power over all things, His complete power to punish and His justice, the human learns to fear his Lord because of his own sins and shortcomings toward Him. At the same time, Allaah's سبحانه و تعالى clear description of His forgiveness and great mercy as well as the generous rewards He grants to the believers for their belief and good deeds increases the human's hope in Allaah سبحانه و تعالى. Hence, all of these aspects of the Qur'aan are intended to help the human know his Lord, have the proper relationship toward Hum and to have the feelings in his heart that make him act properly towards Allaah سبحانه و تعالى.
Thus when one reads the Qur'aan, he should realise that he is reading about his God and Lord. The Qur'aan is answering those basic human questions for him: Who is my Creator and God? What is my relationship to Him? Why did He create me? But, more importantly, Allaah سبحانه و تعالى is telling the human about Himself so the human may draw closer to Him and increase his adoration and worship Him.
That this is one of the overriding purposes of the Qur'aan can be seen in the following hadeeth wherein the Prophetصلى الله عليه وسلم identifies the greatest or most virtuous verse in the Qur'aan: Ubayy Ibn Ka'ab رضي الله عنه narrated that the Messenger of Allaah صلى الله عليه وسلم said to him, "O Abul-Mundhir! Do you know which verse of the Book of Allaah with you is the greatest?" He replied, "Allaah and His Messenger know best." Again the Prophet صلى الله عليه وسلم asked, "O Abul-Mundhir! Do you know which verse of the Book of Allaah with you is the greatest?" He replied, "I said, '[The verse,] Allaah, there is no god worthy of worship besided Him, the Ever-Living, the Ever-Sustaining'"? The Prophet صلى الله عليه وسلم then struck his chest and said, "By Allaah, may knowledge be made pleasant for you oh Abul-Mundhir [as you answered correctly]."