Exodus 9:18

To morrow about this time. That the time was fixed for the beginning of the plague would testify to the king that Jehovah was Lord of heaven and earth, and that the forces of nature, all objects of Egyptian idolatry, were the creatures of His power and subservient to His will. Far from being able to help them, these elements, regarded by the Egyptians as their gods, were under the control of the God of their enemies, and He would now use them as instruments for the punishment of those who worshiped them. How greatly God abhors idolatry!

A very grievous hail. Rain and, more particularly, hail are comparatively rare in Egypt. The region of Cairo has but 2 in. of rainfall annually, and south of Cairo rain is a rare occurrence. Sometimes not a drop of rain falls for years. It is understandable, therefore, that a hailstorm such as that described in vs. 23 and 24 was so extraordinary an experience as to be considered an act of divine punishment (see v. 27).

Since the foundation. This is from another typically Egyptian expression rendered by Moses into Hebrew, which, with numerous others, shows that the author was well acquainted with the Egyptian language. In v. 24 the same thought is expressed by the words “since it became a nation.” Many Egyptian inscriptions refer to the ancient past when their first king united several tribes into one nation.