Shemot 9:34-35

Orthodox Jewish Bible

³⁴ And when Pharaoh saw that the rain and the barad and the thunders were ceased, he sinned yet more, and hardened his lev, he and his avadim.

³⁵ And the lev Pharaoh was hardened, neither would he let the Bnei Yisroel go; as Hashem had spoken by Moshe.