In this Ayah, Allah mentions that He is the only deity, and that He has no partners or equals. He is Allah, the One and Only, the Sustainer, and there is no deity worthy of worship except Him. He is the Most Gracious — Ar-Rahman, the Most Merciful — Ar-Rahim. We explained the meanings of these two Names in the beginning of Surat Al-Fatihah. Shahr bin Hawshab reported that Asma' bint Yazid bin As-Sakan narrated that Allah's Messenger said:
"Allah's Greatest Name is contained in these two Ayah:
{And your Ilah (God) is One Ilah (God - Allah), La ilaha illa Huwa (there is none who has the right to be worshipped but He), the Most Gracious, the Most Merciful.} and:
{Alif-Lam-Mim. Allah! La ilaha illa Huwa (none has the right to be worshipped but He), Al-Hayyul-Qayyum (the Ever Living, the One Who sustains and protects all that exists).} (3:1, 2)"
Then Allah mentions some of the proof that He is alone as the deity, that He is the One who created the heavens and the earth and all of the various creatures between them, all of which testify to His Oneness. Allah said:
{164. Verily, in the creation of the heavens and the earth, and in the alternation of night and day, and the ships which sail through the sea with that which is of use to mankind, and the water (rain) which Allah sends down from the sky and makes the earth alive therewith after its death, and the moving (living) creatures of all kinds that He has scattered therein, and in the veering of winds and clouds which are held between the sky and the earth, are indeed Ayat (proofs, evidences, signs, etc.) for people of understanding.}

Allah said:
{Verily, in the creation of the heavens and the earth...}

Therefore, the sky, with its height, intricate design, vastness, the heavenly objects in orbit, and this earth, with its density, its lowlands, mountains, seas, deserts, valleys, and other structures, and beneficial things that it has. Allah continues:
{...and in the alternation of night and day.}

This (the night) comes and then goes followed by the other (the day) which does not delay for even an instant, just as Allah said:
{It is not for the sun to overtake the moon, nor does the night outstrip the day. They all float, each in an orbit.} (36:40)
Sometimes, the day grows shorter and the night longer, and sometimes vice versa, one takes from the length of the other. Similarly Allah said:
{Allah merges the night into the day, and He merges the day into the night} (57:6)
meaning, He extends the length of one from the other and vice versa. Allah then continues:
{...and the ships which sail through the sea with that which is of use to mankind,}

Shaping the sea in this manner, so that it is able to carry ships from one shore to another, so people benefit from what the other region has, and export what they have to them and vice versa.
Allah then continues:
{...and the water (rain) which Allah sends down from the sky and makes the earth alive therewith after its death}, which is similar to Allah's statement:
{And a sign for them is the dead land. We give it life, and We bring forth from it grains, so that they eat thereof.} (36:33), until:
{which they know not.} (36:36)
Allah continues:
{and the moving (living) creatures of all kinds that He has scattered therein,}

meaning, in various shapes, colors, uses and sizes, whether small or large. Allah knows all that, sustains it, and nothing is concealed from Him. Similarly, Allah said:
{And no moving (living) creature is there on earth but its provision is due from Allah. And He knows its dwelling place and its deposit (in the uterus or grave). All is in a Clear Book (Al-Lawh Al-Mahfuz — the Book of Decrees with Allah).} (11:6)
{...and in the veering of winds ...}

Sometimes, the wind brings mercy and sometimes torment. Sometimes it brings the good news of the clouds that follow it, sometimes it leads the clouds, herding them, scattering them or directing them. Sometimes, the wind comes from the north (the northern wind), and sometimes from the south, sometimes from the east, and striking the front of the Ka'bah, sometimes from the west, striking its back. There are many books about the wind rain, stars and the regulations related to them, but here is not the place to elaborate on that, and Allah knows best.
Allah continues:
{... and clouds which are held between the sky and the earth,}

The clouds run between the sky and the earth to wherever Allah wills of lands and areas.
Allah said next:
{...are indeed Ayat for people of understanding,}

meaning, all these things are clear signs that testify to Allah's Oneness. Similarly, Allah said:
{Verily, in the creation of the heavens and the earth, and in the alternation of night and day, there are indeed signs for men of understanding. Those who remember Allah (always, and in prayers) standing, sitting, and lying down on their sides, and think deeply about the creation of the heavens and the earth, (saying): "Our Lord! You have not created (all) this without purpose, glory to You! (Exalted are You above all that they associate with You as partners). Give us salvation from the torment of the Fire."} (3:190, 191)