The Unseen Belongs Only to Allah...
The term "gayb" (unseen) is used to describe everything that is hidden from a person's senses and concealed from human knowledge. Gayb is that which is not displayed before the human eye, not that which does not exist. What we cannot see, or even explain with our minds, is not non-existent; it is simply what we see but cannot describe.
It is something that people do not yet understand, but which is actually possible. Sometimes it is beyond human knowledge because it has never materialized, and sometimes because it has not yet been noticed.
Then there is a relative and an absolute unseen. The relative unseen is that which is unknown today, here, and according to this context; but which will be known tomorrow, there, and according to that context. The absolute unseen, on the other hand, is that which, due to the nature of human existence, the power of humankind can never reach to know; this is beyond the knowledge of divinity.
One of the most advanced manifestations of Allah's knowledge is His knowledge of the unseen. The Quran does not accept the concept of the unseen for God. The unseen is a concept relevant to humankind.
Say: "None in the heavens and the earth knows the Ghaib (unseen) except Allah, nor can they perceive when they shall be resurrected."
And with Him are the keys of the Ghaib (all that is hidden), none knows them but He. And He knows whatever there is in (or on) the earth and in the sea; not a leaf falls, but he knows it. There is not a grain in the darkness of the earth nor anything fresh or dry, but is written in a Clear Record.
And they say: "How is it that not a sign is sent down on him from his Lord?" Say: "The unseen belongs to Allah Alone, so wait you, verily I am with you among those who wait (for Allah's Judgement)."
And to Allah belongs the unseen of the heavens and the earth. And the matter of the Hour is not but as a twinkling of the eye, or even nearer. Truly! Allah is Able to do all things.
To Allah belongs the Unseen of the heavens and the earth, and to Him all matters are returned. So worship Him and trust in Him. Your Lord is not oblivious of what you do.
Allah will not leave the believers in the state in which you are now, until He distinguishes the wicked from the good. Nor will Allah disclose to you the secrets of the Ghaib (unseen), but Allah chooses of His Messengers whom He pleases. So believe in Allah and His Messengers. And if you believe and fear Allah, then for you there is a great reward.
17. that the two receivers (recording angels) receive, one sitting on the right and one on the left.
18. Not a word does he utter but there is a sentinel by him, ready (to note it).
Therefore, while God knows what is in a person's heart, angels can only know the words that come out of their mouth. Based on this, it can be said that angels also have no share in the unseen.
Even jinn cannot know the unseen:
Then when We decreed death for him [Sulaiman (Solomon)], nothing informed them (jinns) of his death except a little worm of the earth, which kept (slowly) gnawing away at his stick, so when he fell down, the jinns saw clearly that if they had known the unseen, they would not have stayed in the humiliating torment.
Even prophets cannot know the unseen. Prophets only know what God has revealed to them.
Say: "I don't tell you that with me are the treasures of Allah, nor (that) I know the unseen; nor I tell you that I am an angel. I but follow what is revealed to me by inspiration." Say: "Are the blind and the one who sees equal? will you not then take thought?"
Say: "I possess no power of benefit or hurt to myself except as Allah wills. If I had the knowledge of the Ghaib (unseen), I should have secured for myself an abundance of wealth, and no evil should have touched me. I am but a warner, and a bringer of glad tidings unto people who believe."
Some information about the unseen is revealed by Allah to His messengers through divine revelation, and that is how we learn about them. In other words, the knowledge of the unseen known to the messengers is limited to the revelation from Allah.
26. (He Alone) the All-Knower of the Gha'ib (unseen), and He reveals to none His Gha'ib (unseen)."
27. "Except a messenger whom He has chosen: and then He makes a band of watchers march before him and behind him,
28. "That He may know that they have (truly) brought and delivered the Messages of their Lord: and He surrounds (all the mysteries) that are with them, and takes account of every single thing."
After revelation, that information ceases to be hidden. The angels are made watchful eyes so that the messenger may not doubt that the information comes from God.
Revelation is also defined as 'the collection of messages that make the unseen known'. The Quran states that messengers received revelations 'from the unseen'.
This is of the news of the unseen which We reveal unto you, neither you nor your people knew them before this. So be patient. Surely, the (good) end is for the Muttaqun (pious - see V. 2:2)
This is of the news of the Ghaib (unseen) which We reveal by Inspiration to you. You were not (present) with them when they arranged their plan together, and (also, while) they were plotting.
That is from the news of the unseen which We reveal to you. And you were not with them when they cast their pens as to which of them should be responsible for Mary. Nor were you with them when they disputed.
Therefore, claims that someone knows certain things should not be given credence. Otherwise, to claim to know something that God has said He has not shared, that it is unknowable, that it is solely under His control and belongs to Him, is to associate partners with God in one of His attributes and is polytheism (shirk).