Exodus 8:11-15

11The frogs will depart from you and your houses and your officials and your people; they will remain only in the Nile.”

12After Moses and Aaron had left Pharaoh, Moses cried out to the LORD for help with the frogs that He had brought against Pharaoh. 13And the LORD did as Moses requested, and the frogs in the houses, the courtyards, and the fields died. 14They were piled into countless heaps, and there was a terrible stench in the land.

15When Pharaoh saw that there was relief, however, he hardened1 his heart and would not listen to Moses and Aaron, just as the LORD had said.