What is the meaning of, "Have you not seen how your Lord extends the shade, and if He willed, He could have made it stationary? Then We made the sun its guide"?

The noble verse draws attention to Allah Almighty's power and excellent management of the universe, clarifying the states of the shadow: its extension before sunrise and its decrease with the sun's ascent. So, Allah's saying, "Have you not seen how your Lord extends the shadow?" means: Have you not looked at your Lord's handiwork and power in spreading the shadow and its encompassing the earth from dawn until sunrise? And had Allah willed, He could have made it constant and permanent, never to vanish. But He "made the sun its guide," so that the shadow may be known by it. Then, "We withdraw it to Ourselves, a gentle withdrawal," meaning little by little, by means of the sun that falls upon it.