When Prophet Muhammad, sallallahu ^alayhi wa sallam, was asked how this universe started to exist, he said:
“Allah existed [eternally] and nothing else existed with Him. He created the ^Arsh (Throne) [and was positioned] above the water. Then He ordered the Pen to write in the (Guarded) Tablet everything that would happen. Then Allah created the heavens and Earth.” (Related by al-Bukhariyy.)
The Prophet answered this question by first stating that Allah's Existence does not have a beginning, i.e., He is Eternal. There is no one attributed with eternity other than Him. In other words, nothing existed eternally except Allah, and Allah created everything, i.e., He brought all the creation from non-existence into existence.
Allah, ta^ala, did not create all the creations at one time. Had He willed for this, it would have occurred. Rather, in six days, He created the heavens and Earth; and for Earth Allah created rivers, mountains, and valleys. The wisdom of this is to teach us not to be hasty in doing things.
The first creation is water. The Prophet, sallallahu ^alayhi wa sallam, said:
[Innallaha ta^ala khalaqa kulla shay’im minal-ma’.]
Which means: “Allah created everything from water.” (Related by Ibn Hibban.)
This also means that Allah created water before creating light, darkness, Earth, the heavens, the Throne, or the Guarded Tablet. Allah made water the origin for other creations. He created the Throne from water. Then He created the Upper Pen, then the Guarded Tablet. After these creations, Allah created the rest of the creations: the Earth, heavens, animals, mountains, trees, and rivers. Adam, peace be upon him, was of the last kind of creation, humans.
The (^Arsh) Throne: It is a platform with four pillars; it is the largest of Allah's creations. It is also the ceiling of Paradise.
The Prophet, sallallahu ^alayhi wa sallam, said:
Mas-samawatus-sab^u fi jambil-Kursiyyi illa kahalqatin fi ardin falah. Wa fadlul-^Arshi ^alal-Kursiyyi kafadlil-falati ^alal-halqah.(Related by Ibn Hibban.)
This hadith means that the seven heavens in relation to the Kursiyy are like a ring in a very big open space. Likewise, the Kursiyy in relation to the Throne is like a ring in a very big open space. This indicates the huge size of the Throne, which is now carried by four (4) huge angels. It takes a fast bird seven hundred (700) years to cover the distance between the ear lobe and the shoulder of any of these four angels. On the Day of Judgment eight (8) angels will carry the Throne.
The Throne is surrounded by angels. It is not a place for Allah, because Allah is not a body in need of a place.
Imam ^Aliyy, may Allah raise his rank said:
Innallaha, ta^ala, khalaqal-^Arsha idh-haral-liqudratihi wa lam yattakhidh-hu makanal-li Dhatih.
Which means: “Allah created the Throne as an indication of His Power; He has not taken it as a place for Himself.”