Assalamu alaikum.I am asking Allah for something great (its within the scope of religion and permissible). And I have hope that He will grant me it.But I saw a vision at least 2 years before asking Allah for this thing in which I was granted by Allah that which I sought. I saw this dream at a time when I did not even think I will ask Allah for it, nor that such a thing existed.Does this mean or is this a sign that my supplication will be accepted? Can I take my vision as a guarantee from Allah?

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.

This dream is a sign that your supplication has been answered, or that it is a guarantee from Allah about that matter of the unseen.

Therefore, it is not possible to authoritatively say anything about it with certainty.

But you should make this as a reason for thinking good of your Lord and having trust in Him that He will give you what you asked Him for.

One of the reasons for the supplication being answered is certainty that it will be answered.

Abu Hurayrah narrated that the Prophet said: “Supplicate Allah when you are assured of being answered, and know that Allah does not answer a supplication which comes from a careless and inattentive heart.” [At-Tirmidhi]

So strive to achieve the reasons for the supplication to be answered, and do not worry about the answer, but supplicate Allah while fulfilling the reasons for the supplication being answered.

It is worth mentioning here that the answer to the supplication does not mean that the one who supplicates be given the same thing as he asked for; rather, Allah, Glory be to Him, may give him what is better than what he asked for.

Abu Sa’eed al-Khudri narrated that the Prophet said: “Any Muslim who supplicates without entailing a sin or breaking ties with kinship (in his supplications) except that Allah gives him one of these three things: either his supplication is granted immediately in this world, or that it will be kept for him for the Hereafter, or that He repels from him an evil equivalent to that which he supplicated for.” The Companions said: “In this case we will supplicate Allah as much as we can.” The Prophet replied: “Allah is more and ready to answer more than what you can ask for.” [Ahmad]

Allah Knows best.