16 Then the Lord said to Moses, "Say to Aaron, 'Stretch out your rod and strike the dust of the earth, that it may become gnats throughout all the land of Egypt.'" 17 And they did so; Aaron stretched out his hand with his rod, and struck the dust of the earth, and there came gnats on man and beast; all the dust of the earth became gnats throughout all the land of Egypt. 18 The magicians tried by their secret arts to bring forth gnats, but they could not. So there were gnats on man and beast. 19 And the magicians said to Pharaoh, "This is the finger of God." But Pharaoh's heart was hardened, and he would not listen to them; as the Lord had said.
Matthew Henry's Commentary on Exodus 8:16-19
Commentary on Exodus 8:16-19
(Read Exodus 8:16-19)
These lice were produced out of the dust of the earth; out of any part of the creation God can fetch a scourge, with which to correct those who rebel against him. Even the dust of the earth obeys him. These lice were very troublesome, as well as disgraceful to the Egyptians, whose priests were obliged to take much pains that no vermin ever should be found about them. All the plagues inflicted on the Egyptians, had reference to their national crimes, or were rendered particularly severe by their customs. The magicians attempted to imitate it, but they could not. It forced them to confess, This is the finger of God! The check and restraint put upon us, must needs be from a Divine power. Sooner or later God will force even his enemies to acknowledge his own power. Pharaoh, notwithstanding this, was more and more obstinate.