Exodus Chapter 9 Verse 32 - 35
32.) But the wheat and the spelt were not struck, for they had not grown up.
33.) Moses went out of the city from Pharaoh, and spread abroad his hands to Yahweh; and the thunders and hail ceased, and the rain was not poured on the earth.
34.) When Pharaoh saw that the rain and the hail and the thunders were ceased, he sinned yet more, and hardened his heart, he and his servants.
35.) The heart of Pharaoh was hardened, and he didn't let the children of Israel go, just as Yahweh had spoken through Moses.