Overall meaning : We have sent you, people, a messenger—Muhammad, may Allah bless him and grant him peace—to bear witness for those who follow and believe him and to bear witness against those who oppose and deny him, just as We sent forth a messenger—Moses, peace be upon him—to Pharaoh. Pharaoh, however, disobeyed Moses and denied him, and so We utterly destroyed him and his forces by drowning them all in the sea.
If you persist in your unbelief, how will you, then, guard yourselves against the horrors of the Day of Resurrection that will turn children hair grey—the day on which the very sky will split asunder due to its terrors? Allah’s promise will inevitably be fulfilled. This is but an admonition which will benefit only the God-fearing. Whoever, therefore, wishes to follow a way leading to his Lord by believing in Him and obeying His commands should do so.