And the Egyptians shall know that I am the Lord,.... Jehovah, the one only true and living God; this they should know by the judgments executed upon them, and be obliged to acknowledge it: when I stretch forth mine hand upon Egypt: especially the last time, to destroy the firstborn: and bring out the children of Israel from among them; by which it would appear that he was mightier than they, and obtained the end for which the plagues were inflicted on them.