Exodus 9:6-7

6So the Lord did this thing on the next day, and 1all the livestock of Egypt died; 2but not one of the livestock of the sons of Israel died. 7And Pharaoh sent men, and they learned that, behold, not even one of the livestock of Israel was dead. But 3the heart of Pharaoh was 4hardened, and he did not let the people go.