And God said, "Let there be lights in the expanse of the heavens to separate the day from the night. And let them be for signs and for seasons, and for days and years, 15and let them be lights in the expanse of the heavens to give light upon the earth." And it was so. 16And God made the two great lights--the greater light to rule the day and the lesser light to rule the night--and the stars. 17And God set them in the expanse of the heavens to give light on the earth, 18to rule over the day and over the night, and to separate the light from the darkness. And God saw that it was good. 19And there was evening and there was morning, the fourth day.
Matthew Henry: “[Learn from this] (2.) The duty and wisdom of daily worshipping that God who made all these things, and made them to be that to us which they are. The revolutions of the day and night oblige us to offer the solemn sacrifice of prayer and praise every morning and evening.
Clay Miller: In America we think of our days as being for work and play. That is true in a sense. We are to work. We are to rest. Those are not inherently wrong of course. But God created the sun, moon and stars to pretty much delineate between day and night. He gave us daytime and nighttime. And our duty and our joy is to be transformed from the casual thoughtlessness of just going through the motions, and rather think, “How can I use the daytime to glorify God. How can use the nighttime to glorify God. Daytime is an amazing time. We see the whole world lit up. We see the inside of this bubble we live in called the atmosphere. Nighttime is amazing too. We see past the bubble more clearly and see that there is a vast universe out there. God lights up the earth and atmosphere in the day to show off His creation here. Then at night He reminds us of how infinitely powerful and how endless He is by showing us a glimpse of the size of our universe. What we see is not the great thing…though it is great. The great One is the Creator of it all!