Dreams have significant role in the life of man. Allah (SWT made Mohammed (PBUH) see an unrealistic image before battle of Badr. This image indicated that the enemy is weak and they are few in number. With this image gave Allah (SWT) self-confidence for Muslims. At the same time this event shows that dreams are not always realistic. According to the particular occasion Allah wants to accomplish His goal.
Therefore, the person who reads the dream transgress the border of unseen world and makes fake job when he interprets dreams literally. The real message and orienting strength of a dream is in the hand of Allah (SWT):
Remember in thy dream Allah showed them to thee as few: if He had shown them to thee as many, ye would surely have been discouraged, and ye would surely have disputed in (your) decision; but Allah saved (you): for He knoweth well the (secrets) of (all) hearts. (Quran 8:43)
Here you are another example. Abraham got the order from his Lord in his dreams to sacrifice his son:
Then, when (the son) reached (the age of) (serious) work with him, he said: "O my son! I see in vision that I offer thee in sacrifice: Now see what is thy view!" (The son) said: "O my father! Do as thou art commanded: thou will find me, if Allah so wills one practising Patience and Constancy!" (Quran 37:102)
And here you are the interpretation of dreams:
It is Allah that takes the souls (of men) at death; and those that die not (He takes) during their sleep: those on whom He has passed the decree of death, He keeps back (from returning to life), but the rest He sends (to their bodies) for a term appointed verily in this are Signs for those who reflect. (Quran 39:42)
The mystery of life and death, sleep and dreams, is a fascinating enigma, of which the solution is perhaps beyond the ken of man. A vast mass of superstition as well as imaginative and psychological literature has grown up about it. But the simplest and truest religious doctrine is laid down here in a few words. In death we surrender our physical life, but our soul does not die; it goes back to a plane of existence in which it is more conscious of the realities of the spiritual world: "Allah takes the soul". The mental processes (and certainly volition) are also suspended in sleep, except that in ordinary dreams there is a medley of recollections, which often present vividly to our consciousness things that do not or cannot happen in nature as we know it in our coordinated minds. But there is another kind of dream which is rarer-one in which the dreamer sees things as they actually happen, backwards or forwards in time, or in which gifted individuals see spiritual truths otherwise imperceptible to them. How can we explain this? It is suggested that our soul or personality, -that something which is above our animal life-is then in a plane of spiritual existence akin to physical death (see last note), when we are nearer to Allah. In poetic imagery, Sleep is "twin-brother to Death".
If we contemplate these things, we can see more clearly many spiritual truths: e.g. 1. that our bodily life and death are not the whole story of our existence; 2. that in our bodily life we may be dead to the spiritual world, and in our bodily death, may be our awakening to the spiritual world; 3. that our nightly Sleep, besides performing the function of rest to our physical life, gives us a foretaste of what we call death, which does not end our personality; and 4. that the Resurrection is not more wonderful than our daily rising from Sleep, "twin-brother to Death".