For if you refuse to let them go, and still hold them,
Exodus 9:2
Surrounding context
9:1 Then the LORD said to Moses, "Go in to Pharaoh and tell him, "Thus says the LORD God of the Hebrews: "Let My people go, that they may serve Me.
9:2 For if you refuse to let them go, and still hold them,
9:3 behold, the hand of the LORD will be on your cattle in the field, on the horses, on the donkeys, on the camels, on the oxen, and on the sheep--a very severe pestilence.