Moses
Exodus 9:12ESV·traditional attribution

But the LORD hardened the heart of Pharaoh, and he did not listen to them, as the LORD had spoken to Moses.

Matthew Henry Presbyterian @wholebiblehenry

Observe here, concerning the plague of boils and blains, I. When they were not wrought upon by the death of their cattle, God sent a plague that seized their own bodies, and touched them to the quick. If less judgments do not do their work, God will send greater.

Commenting on Exodus 9:8-12

John Gill Reformed Baptist @doctorgill

And the Lord hardened the heart of Pharaoh,.... He having often, and so long hardened his own heart, God gave him up to judicial hardness of heart, to his own corruptions, the temptations of Satan, and the lying magicians about him, to make an ill use of everything that offered to him, and put a wrong construction on all that befell him, so that whatever...

Jamieson-Fausset-Brown Reformed @jfbcommentary

PLAGUE OF BOILS. (Exo 9:8-17) Take to you handfuls of ashes, &c.--The next plague assailed the persons of the Egyptians, and it appeared in the form of ulcerous eruptions upon the skin and flesh (Lev 13:20; Kg2 20:7; Job 2:7). That this epidemic did not arise from natural causes was evident from its taking effect from the particular action of Moses done in the sight of Pharaoh.

Commenting on Exodus 9:8-17