Exodus 9:5-7

Amplified Bible

⁵ The Lord set a [definite] time, saying, “Tomorrow the Lord will do this thing in the land.” ⁶ And the Lord did this thing the next day, and all [kinds of] the livestock of Egypt died; but of the livestock of the Israelites, not one died. ⁷ Then Pharaoh sent [men to investigate], and not even one of the livestock of the Israelites had died. But the heart of Pharaoh was hardened [and his mind was firmly set], and he did not let the people go.