John Gill Commentary Exodus 7:3

"And I will harden Pharaoh`s heart, and multiply my signs and my wonders in the land of Egypt." — Exodus 7:3 (ASV)

And I will harden Pharaoh's heart
(See Gill on Exodus 4:21) and multiply my signs and my wonders in the land of Egypt ;
work one miracle and wonderful sign after another, until all those intended are performed, which he had given Moses power to do, until the end was achieved: the letting go of the children of Israel.