Nights and Days are two signs of Allah SWT

"They ask thee, (O Muhammad sal-allahu-alleihi-wasallam), of new moons, say: They are fixed seasons for mankind and for the pilgrimage."    [2. Surah Al-Baqarah : Ayah 189]


"He causes the dawn to break; and He has made the night for rest, and the sun and the moon for reckoning; this is an arrangement of the Mighty, the Knowing. And He it is Who has made the stars for you that you might follow the right way thereby in the darkness of the land and the sea; truly We have made plain the communications for a people who know."  [6. Surah Al-An'am : Ayah 96-97] 


"He throws the veil of night over the day, which it pursues incessantly; and (He created) the sun and the moon and the stars, made subservient by His command."     [7. Surah Al-Araaf : Ayah 54]


"He it is Who appointed the sun a splendour and the moon a light, and measured for her stages, that ye might know the number of the years, and the reckoning. Allah created not (all) that save in truth. He detaileth the revelations for people who have knowledge."     [10. Surah Yunus : Ayah 5]


"And He has made subservient for you the night and the day and the sun and the moon, and the stars are made subservient by His commandment; most surely there are signs in this for a people who ponder."     [16. Surah Al-Nahl : Ayah 12]


"And We have made the night and the day two signs, then We have made the sign of the night to pass away and We have made the sign of the day manifest, so that you may seek grace from your Lord, and that you might know the numbering of years and the reckoning; and We have explained everything with distinctness."   [17. Surah Bani Israel : Ayah 12]

"Blessed is He Who made the constellations in the heavens and made therein a lamp and a shining moon. And He it is Who made the night and the day to follow each other for him who desires to be mindful or desires to be thankful."        [25. Surah Furqan : Ayah 61-62]


"He causes the night to enter in upon the day, and He causes the day to enter in upon the night, and He has made subservient (to you) the sun and the moon; each one follows its course to an appointed time; this is Allah, your Lord, His is the kingdom; and those whom you call upon besides Him do not control a straw."   [35. Surah Fatir : Ayah 13]