7:3 heart. The Hebrew is a broad term describing the center of feeling, thinking, and willing. The Lord causes Pharaoh’s heart to become hard (lit. “difficult”), not by implanting evil in it, but by giving it over to its evil direction without restraint (Rom. 1:24, 26, 28). Paul contrasts hardening with showing mercy (Rom. 9:18). God’s judgment on Pharaoh issued in mercy to Israel, Egypt, and the nations as they saw His power to save.
though I multiply. Or, “in order that I might multiply.”
my signs and wonders. These are the nine plagues and ten miracles of 7:9–11:10, culminating in the death plague.