Translation:

4. If (such) were Our Will We could send down to them from the sky a Sign to which they would bend their necks in humility.

Notes (Tafseer)

3140. If it had been Allah's Will and Plan to force people's will, He could quite easily have forced the Makkans. But His Will and Plan work differently. His revelation is meant to train man's own will so that it conforms to Allah's beneficent purpose.