Pharaoh

But Pharaoh defied the messenger, so We seized him with a crushing grip.

73:16But Pharaoh rebelled against the messenger, whereupon We seized him with no gentle grip.

So how will you guard yourselves, if you disbelieve, against a Day that will turn children grey?

73:17Then how, if ye disbelieve, will ye protect yourselves upon the day which will turn children grey,

The sky will split apart from its burden. That promise is bound to be fulfilled.

73:18The very heaven being then rent asunder. His promise is to be fulfilled.