God will punish the Egyptians, not only the people, but also their gods (Exodus 12:12; Numbers 33:4). His purpose is the liberation of Israel (compare with Exodus 3:8; Exodus 6:6).
This is how Israel becomes a nation that serves the Lord, a nation that knows that God liberated them (Exodus 6:7) and a nation that sings his praises (see Exodus 15:1–27).
4 Pharaoh will not listen to you. Then I will lay my hand on Egypt and bring my hosts, my people the children of Israel, out of the land of Egypt by great acts of judgment.