What does Exodus 9:5 mean?

The Lord has promised another plague on Egypt (Exodus 3:20) because the king refuses to release Hebrew slaves (Exodus 9:1–3). This disaster will be terrible, but it will only affect Egyptian animals. Hebrew flocks will be free from danger (Exodus 9:4). That helps to prove that this is a supernatural event, caused by a God who makes a distinction between His chosen people and the rest of the world. It emphasizes that Egyptian livestock idols such as Hathor or Apis are powerless.

Another proof that this is supernatural is the exact schedule offered by Moses. The timing of "tomorrow" has already been mentioned three times in Exodus (Exodus 8:10, 23, 29). The plagues of hail (Exodus 9:18) and locusts (Exodus 10:4) will also be predicted precisely one day in advance. The tenth plague, involving the death of firstborn males, would offer a sudden nighttime judgment (Exodus 11:4; 12:29).

God's timing varies throughout Scripture. Some prophecies have yet to be fulfilled. For others, God gave a specific timeline. Still others have both short-term fulfillment and long-term fulfillment, meaning the prophecy proved true within a brief time and had a deeper meaning that would be fulfilled in a longer period. In all these instances, the Lord's timing is perfect. While from our human perspective God's timing may seem slow, Peter reminds believers that with the Lord one day is as a thousand years, and a thousand years as one day (2 Peter 3:8). He tarries because He is patient and desires all to come to repentance (2 Peter 3:9).