Hail was the seventh plague God brought upon Egypt. "Give an order now to bring your livestock and everything you have in the field to a place of shelter, because the hail will fall on every man and animal that has not been brought in and is still out in the field, and they will die." But wait a minute! "All the livestock of the Egyptians died" in the fifth plague! What was left to be killed by hailstones except the people left out to work (poor blokes--surely they weren't Israeli slaves!)?