Allah's statement,

فَالِقُ الإِصْبَاحِ وَجَعَلَ اللَّيْلَ سَكَنًا ...

(He is the) Cleaver of the daybreak. He has appointed the night for resting,

means, He is the Creator of light and darkness.

Allah said in the beginning of the Surah, وَجَعَلَ الظُّلُمَاتِ وَالنُّورَ (And originated the darkness and the light).

Indeed, Allah causes the darkness of the night to disappear and brings forth the day, thus bringing brightness to the world and light to the horizon, while dissipating darkness and ending the night with its depth of darkness and starting the day with its brightness and light.

Allah said,

يُغْشِى الَّيْلَ النَّهَارَ يَطْلُبُهُ حَثِيثًا

He brings the night as a cover over the day, seeking it rapidly. (7:54)

In this Ayah, Allah reminds of His ability to create diversified things in opposites, testifying to His perfect greatness and supreme power. Allah states that He is the Cleaver of the daybreak and mentioned its opposite, when He said, وَجَعَلَ اللَّيْلَ سَكَنًا (He has appointed the night for resting), meaning, created darkness, in order for the creation to become halt and rest during it.

Allah said in other Ayat,

وَالضُّحَى

وَالَّيْلِ إِذَا سَجَى

By the forenoon. And by the night when it is still. (93:1-2)

وَالَّيْلِ إِذَا يَغْشَى

وَالنَّهَارِ إِذَا تَجَلَّى

By the night as it envelops. And by the day as it appears in brightness. (92:1,2)

and,

وَالنَّهَارِ إِذَا جَلَّـهَا

وَالَّيْلِ إِذَا يَغْشَـهَا

And by the day as it shows up (the sun's) brightness. And by the night as it conceals it. (91:3-4)

Allah's statement,

... وَالشَّمْسَ وَالْقَمَرَ حُسْبَانًا ...

...And the sun and the moon for reckoning.

means, the sun and the moon have specific orbits, according to a term appointed with magnificent precision that never changes or alters. Both the sun and the moon have distinct positions that they assume in summer and winter, effecting changes in the length of night and day.

Allah said in other Ayat,

هُوَ الَّذِى جَعَلَ الشَّمْسَ ضِيَآءً وَالْقَمَرَ نُوراً وَقَدَّرَهُ مَنَازِلَ

It is He Who made the sun a shining thing and the Moon as a light and measured out stages for it. (10:5)

لاَ الشَّمْسُ يَنبَغِى لَهَآ أَن تدْرِكَ القَمَرَ وَلاَ الَّيْلُ سَابِقُ النَّهَارِ وَكُلٌّ فِى فَلَكٍ يَسْبَحُونَ

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)

And,

وَالشَّمْسَ وَالْقَمَرَ وَالنُّجُومَ مُسَخَّرَتٍ بِأَمْرِهِ

The sun and the moon; and the stars are subjected by His command. (16:12)

Allah's statement,

... ذَلِكَ تَقْدِيرُ الْعَزِيزِ الْعَلِيمِ ﴿٩٦﴾

Such is the measuring of the Almighty, the All-Knowing.

means, all of this occurs according to the decree and due measurement of the Almighty Who is never resisted or contradicted. He is the Knower of all things and nothing ever escapes His knowledge, not even the weight of an atom on earth or in heavens.

Allah often mentions the creation of the night, the day, the sun and the moon and then ends His Speech by mentioning His attributes of power and knowledge, as in this Ayah above (6:96), and in His statement,

وَءَايَةٌ لَّهُمُ الَّيْلُ نَسْلَخُ مِنْهُ النَّهَارَ فَإِذَا هُم مُّظْلِمُونَ

وَالشَّمْسُ تَجْرِى لِمُسْتَقَرٍّ لَّهَـا ذَلِكَ تَقْدِيرُ الْعَزِيزِ الْعَلِيمِ

And a sign for them is the night, We withdraw there from the day, and behold, they are in darkness. And the sun runs on its fixed course for a term. That is the decree of the Almighty, the All-Knowing. (36:37-38)

In the beginning of Surah Ha-Mim As-Sajdah, after mentioning the creation of the heavens and earth and all that is in them, Allah said:

وَزَيَّنَّا السَّمَآءَ الدُّنْيَا بِمَصَـبِيحَ وَحِفْظاً ذَلِكَ تَقْدِيرُ الْعَزِيزِ الْعَلِيمِ

And We adorned the nearest (lowest) heaven with lamps (stars) to be an adornment as well as to guard. Such is the decree of Him, the Almighty, the All-Knower. (41:12)

Allah said next,