Allah (SWT) knows about Himself and knows everything about His creations. In this category, there is nothing 'Unseen' for Allah (SWT). Therefore, whenever we talk about 'Unseen', it will be with reference to creatures and not with reference to Allah (SWT).
(1) It is in Quran - " Say (O'Prophet - SAWS) I have no power over any good or harm to myself except as Allah (SWT) wills. If I had knowledge of the unseen, I should have multiplied all good and no evil should have touched me. I am but a warner and a bringer of glad tidings to those who have faith". ( Al-Araf- 188).
(2) It is in Quran - " With Him are the keys of the unseen, the treasures that none knows but He. He knows whatever there is on the earth and in the sea. Not a leaf doth fall but with His knowledge: there is not a grain in the darkness (or depths) of the earth, nor anything fresh or dry (green or withered), but is (inscribed) in a record clear (to those who can read)". ( Al-An'aam - 59).
(3) It is in quran - " (Say O'Prophet - SAWS) None in the heavens or on earth, except Allah (SWT), knows what is hidden; nor can they perceive when they shall be raised up (for Judgment) - (An-Namal - 65).
(4) It is in Quran - "Aalimul Ghaibi wash Shahadah" (Al-Hashr - 22) - meaning Allah (SWT) knows everything that is hidden and visible to His creatures.
The above Quranic verses confirm the fact that Allah (SWT) knows the minutest details about His creatures. He also knows about the creatures who will be created in future or the creatures that will remain hidden from the people (for ever). Thus we cannot refer knowledge of Unseen towards Allah (SWT). For Him, everything is "seen".
When Allah (SWT) says He has the knowledge of unseen, it means that He has knowledge about everything that is unseen by human beings. Therefore, the reference of 'unseen' is related to Human beings, not with Allah (SWT).
There are different categories of Knowledge of Unseen given by Allah (SWT) to his chosen servants.
It is in Quran - 'Those who believe on the 'Unseen', and establish Salah and spend from what We (Allah - SWT) has given them. (Al-Baqara - 3).
- (i) In the first category of Unseen, Allah (SWT) bestows the knowledge about (a) Himself (Zaat), (b) His attributes (Sifaat), (c) how the cosmos was created, (d) how life is being nurtured in the cosmos, (e) what is the purpose of our creation and (f) what is the right path for our salvation. This knowledge of 'Unseen' is generally bestowed upon the Prophets.
In this category, 'the knowledge of Unseen' in its most comprehensive and absolute format, is naturally associated with Prophet Mohammad (SAWS) as he is 'Sayyidul Anbiyaa' (SAWS) (Chief of All Prophets - Alaihis salaam ajma'een) and 'Sayyidul Khalaa'eq' (Master/origin/root of all Creations) and "Rahmatul lil Aalameen" (Mercy upon all worlds).
It is in Quran - "Wa allamat ma'alam takun ta'alam - meaning 'And We (Allah -SWT) taught you (O'Prophet - SAWS) about the things you did not know'.
It is in Quran The Unity of Allah (SWT) is pure, who took His Servant (Mohammad Rasulullah SAWS) in one night from the honored mosque (Masjid-e-Haraam) to the Al Aqsa mosque around which We have given abundance of virtue, so that We (Allah - SWT) show him our signs and traces of Omnipotence (which were unseen by any one in the cosmos). Without doubt He is the (only) one who sees and listens. (Bani Israel 1).
It is in Quran The Mighty in power (Allah SWT) has offered him (Prophet Mohammad SAWS) the knowledge. So (equipped), he stood well poised. (With the perfect vision attained) at the highest horizon. Then he (the Prophet SAWS) approached closer and hung (by Allah -SWT). Then (both) closed up like two bows, and indeed more closely. And He revealed to His servant (Prophet Mohammad SAWS) What He wanted to reveal. The heart of Prophet Mohammad (SAWS) did not distrust what he saw. Will you people wrangle over what he beheld (saw). For indeed he beheld Him (Allah SWT) yet again. Near the Lote tree lying farthest beyond which no one can go. Lying close to the Heaven of Rest. When the Lote tree was being enveloped by what it was to be enveloped with (a mystery not disclosed). His (Prophet Mohammad SAWS) sight did not blink or did it miss anything. Indeed he saw clearly the greatest of the signs of his Lord. (An-Najm 1-18).
It is in Hadith (Tirmidhi and Mishkaat) - It is narrated by Hazrat Ibn Abbas (RU), he said that the Prophet (SAWS) said - 'My Sustainer came to me in a very good face and said, O'Mohammad (SAWS), I submitted 'Yes, my Sustainer (Rab), present', He said, do you know that the sublime angels argue with each other in what?, I submitted, I do not know'. Then He placed His hands of Omnipotence (Dust-e-Qudrah) in between my shoulders and I found the coolness of the hand into my chest and then I knew whatever there is, in the skies and the earth.
It is in Hadith - the Prophet (SAWS) said'Ooteetul ilmal awwaleena wal Aakhireen" (Meaning - I have been bestowed with the knowledge of the past (present) and future creations.
Prominent scholars like al-Haytami, al-Qari, Abul Su`ud, and many others stated that the Prophet (SAWS) had knowledge of everything encompassed in the tablet and pen.
The sources of knowledge of Unseen of Prophet Mohammad (SAWS) are: (a) Direct, (b) Indirect, and (c) Prophetic Vision.
Direct Knowledge - The above Ahadith and verses refer to the direct knowledge bestowed upon him.
Indirect knowledge - The Quran, was sent to Prophet Mohammad (SAWS) as official document via Hazrat Jibreel (AS).
Prophetic Vision - In addition to the above two sources, the knowledge of Unseen was disclosed to Prophet Mohammad (SAWS) by way of "Prophetic vision". In this category, the World of Souls (Aalam-e-Arwah), the World of Similitude (Aalam-e-Mithaal) and Prophetic Dreams are included.
There are many Ahadith that describe the events unfolded in the past or that will happen in future till the Day of Resurrection and beyond. This knowledge was bestowed to Prophet Mohammad (SAWS) directly from "Ilm-e-Elahi" (Allah's -SWT knowledge). Under this category he might have witnessed how things unfolded in the past or will happen in future. Or may be he was simply informed about them by Allah (SWT) directly.
It is in Hadith - Abu Dharr (RU) narrates; When the Messenger of Allah (SAWS) left us, there was not a bird that flies in the sky but that he had given us some knowledge about it. (Ibn Hanbal & Tabarani)
It is in Hadith - Prophet Mohammad (SAWS) said that Uthman (RU) will be martyred whilst reciting Quran. Perhaps Allah (SWT) will have him wearing a shirt. They will want to remove it and his blood will fall on the words of Allah (SWT) (Bukhari & Muslim).
It is in Hadith - Anas (RU) narrates that the Beloved Messenger of Allah (SAWS), Abu Bakr Siddeeq (RU), Umar bin Khattab (RU) and Uthman bin Affan (RU) were climbing Mount Uhud. The mountain shook from under them, the Beloved Messenger of Allah (SAWS) said Be firm Uhud, a Prophet, a Truthful person (Siddeeq) and Two martyrs are walking on you (Bukhari & Ibn Majah).
Why Quran was sent via Hazrat Jibreel (AS)?
It is for the simple reason that people should see from their eyes how official documents are sent to Prophet Mohammad (SAWS) from Allah (SWT).