Observe in this plague the magicians are included as partakers. It should seem that in direct defiance of their own confession, Exodus 8:19. they still attempted to confront God's messenger, and thereby did their utmost to harden Pharaoh's heart. See Act 13:8-11; 2 Timothy 3:8-9.
Related Commentaries of Exodus 9:10
Exodus 9:10-11
10 And they took ashes of the furnace, and stood before Pharaoh; and Moses sprinkled it up toward heaven; and it became a boil breaking forth with blains upon man, and upon beast.
11 And the magicians could not stand before Moses because of the boils; for the boil was upon the magicians, and upon all the Egyptians.