Miracle of the Shadow in the Quran

 Have you not seen how your Lord extended the shadow? If He had willed, He could have made it stationary. Then We made the sun its guide.

(Al-Furqan: 45)

We read from the intermediate interpretation of Tantawi:

Extending the shadow means: He spread it out and made it wide and moving with the movement of the earth facing the sun, and He made it a place where people can seek shade from the glare and heat of the sun, and find rest there after fatigue. This is from the great mercy of your Lord towards His servants.

And His statement, the Most High: And if He had willed, He could have made it stationary is an interpolated clause to clarify one aspect of His power, the Most High. That is: “And if He had willed” - Glory be to Him - He would have made this shadow “still” - that is: fixed, always stable, and in one state, such that the sun would not remove it, nor would it disappear from the face of the earth. But He - Glory be to Him - did not will that, because the interest and benefit of His creation is in its existence in the manner in which He created it according to His wisdom.