And seven days were fulfilled. — These words seem to mark the duration of the first plague, which was the longer because Pharaoh made no submission at all in consequence of it. Obtaining sufficient water for his own purposes (see the comment on Exodus 7:23), he thought little of its continuance.
Related Commentaries of Exodus 7:25
Exodus 7:25
25 And seven days were fulfilled, after that the LORD had smitten the river.