5 The LORD set a time and said, “Tomorrow the LORD will do this in the land.”

Read Exodus 9:5 Using Other Translations

And the LORD appointed a set time, saying, To morrow the LORD shall do this thing in the land.
And the LORD set a time, saying, "Tomorrow the LORD will do this thing in the land."
The LORD has already set the time for the plague to begin. He has declared that he will strike the land tomorrow.’”