Not upon the Israelites, whom he hereby exempts from the number of Pharaoh's people and subjects, and owns them for his peculiar people. The frogs did not only invade their houses, but assault their persons, which is not strange, considering that they were armed with a Divine commission and power.
Related Commentaries of Exodus 8:4
Exodus 8:4
4 And the frogs shall come up both on thee, and upon thy people, and upon all thy servants.