Pestilence; not properly so called, but largely, as the word is used Hosea 13:14, meaning with an utter and irrecoverable destruction. This relates partly to the killing of the first-born, which plague did more immediately and nearly concern both him and his people, and principally to their destruction in the Red Sea.
Related Commentaries of Exodus 9:15
Exodus 9:15
15 For now I will stretch out my hand, that I may smite thee and thy people with pestilence; and thou shalt be cut off from the earth.