The finger of God - This expression is thoroughly Egyptian; it need not imply that the magicians recognized Yahweh, the God who performed the marvel. They may possibly have referred it to as a god that was hostile to their own protectors.
Related Commentaries of Exodus 8:19
Exodus 8:19
19 Then the magicians said unto Pharaoh, This is the finger of God: and Pharaoh's heart was hardened, and he hearkened not unto them; as the LORD had said.