إِنَّ اللَّهَ عِندَهُ عِلْمُ السَّاعَةِ وَيُنَزِّلُ الْغَيْثَ وَيَعْلَمُ مَا فِي الْأَرْحَامِ ۖ وَمَا تَدْرِي نَفْسٌ مَّاذَا تَكْسِبُ غَدًا ۖ وَمَا تَدْرِي نَفْسٌ بِأَيِّ أَرْضٍ تَمُوتُ ۚ إِنَّ اللَّهَ عَلِيمٌ خَبِيرٌ (34)
(31:34) Surely Allah alone has the knowledge of the Hour. It is He Who sends down the rain and knows what is in the wombs, although no person knows what he will earn tomorrow, nor does he know in which land he will die. Indeed, Allah is All-Knowing, All-Aware. *63
*63) This verse is, in fact an answer to the disbelievers' question as to when the Hour of Resurrection will come, which they asked when they heard the Holy Prophet mention it and the promise of the Hereafter, again and again. The Qur'an has answered this sometimes by citing the question and sometimes without citing it, because the addressees knew what they were asking. This is one of those verses which answer the question without citing the question itself.
The first sentence: 'AIIah alone has the knowledge of the Hour", is the real answer to the question. The four sentences that follow constitute the argument to support it. The argument means this: "O man. you do not have the knowledge even about those things with which you are most closely and intimately concerned in life. How then can it be possible for you to know as to when will the whole world cane to an end? Your prosperity and adversity mainly depend on the rain. But its control and regulation is entirely in the hand of Allah. He sends down the rain whenever and wherever and in whatever measure He pleases and withholds it whenever he pleases. You do not at aII know how much of the rain will fall at a particular place at a particular time and which land will remain without it, and which land will be adversely affected in spite of it. Your wives conceive by your own sperm-drop, which perpetuates your race in the future, but you do not know what is taking shape in their wombs, and in what form and with what good or evil it will emerge. You do not even know what you are going to meet with the next day A sudden accident can change your destiny; but you are unaware of it even a minute before its occurence. You do not know where your present life will eventually cane to an end. AIlah has kept all this information with Himself alone; and has not given you any knowledge of any of these. You actually desire that you should have the knowledge of each of these things so that you may make necessary preparations beforehand, but you have no other course open to you than to depend only on Allah's decree and disposal in these matters. Likewise, about the end of the world also there is no alternative but to rely on Allah's decree and decision. The knowledge of this also has neither been given to anybody, nor can it be given." Here, another thing also should be understood well, and it is this: This verse dces not give a list of the unseen and hidden things, which are known to no one but Allah. Here only some of the most apparent things have been pointed out only to serve as an illustration. These are the things with which man is most deeply and intimately concerned, yet he is unaware of them. From this it would be wrong to conclude that these are the only five unseen and hidden things which are known to no one but AIIah. As a matter of fact, ghaib applies to every such thing which is hidden from the creation but is in the knowledge of Allah, and such things are countless and limitless. (For a detailed discussion of this, see An-Naml: 65 and the E.N.'s thereof).