Charles Ellicott Commentary Exodus 9:7

"And Pharaoh sent, and, behold, there was not so much as one of the cattle of the Israelites dead. But the heart of Pharaoh was stubborn, and he did not let the people go." — Exodus 9:7 (ASV)

Pharaoh sent. —Pharaoh evidently did not believe it was possible that there could be such a widespread destruction of the Egyptian cattle without the Hebrew cattle suffering at all. He therefore sent persons to inquire and report on the facts. These persons found Moses' announcement fulfilled to the letter. This was the more surprising, as Goshen consisted mainly of the low, flat tract bordering on the Menzaleh marshes.

The heart of Pharaoh was hardened. —Even the exact correspondence of the result with the announcement did not soften the king's heart. It remained dull and unimpressed—literally, “heavy” (kâbêd). Loss of property would not much distress an absolute monarch, who could easily exact the value of what he had lost from his subjects.