Allah tells us about the signs He created that are indicative of His complete power and great might. He made the rays that come forth from the bright sun as the source of light and made the beams that come forth from the moon as light. He made them of two different natures, so they would not be confused with one another. Allah made the dominion of the sun in the daytime and the dominion of the moon in the night. He ordained phases for the moon, where it starts small then its light increases until it completes a full moon. Then, it begins to decrease until it returns to its first phase at the conclusion of the month.
Allah then stated ”Allah did not create this but in truth.” That is, He did not create that for amusement but with great wisdom and perfect reasoning.
Allah further stated
”Verily, in the alternation of the night and the day and in all that Allah has created in the heavens and the earth…” meaning that the day and the night alternate, when one arrives, the other goes, and so on, with no errors. And the signs that Allah has created indicate his greatness.
Allah said; ”Ayat for those who have Taqwa” meaning those who fear Allah’s punishment, wrath and torment.
From Tafsir bn Kathir.