What does Exodus 9:3 mean?
God warns that His wrath will come on Egypt if Pharaoh does not let the people go. God's power to punish those who defy Him is described using the phrase "the hand of the Lord." This expression is used later (Exodus 16:3) as another reference to God's judgment. In Deuteronomy 2:15, the "hand of the Lord" is also mentioned as an instrument of divine wrath (also see Joshua 22:31; Judges 2:15). In Joshua 4:24, "the hand of the Lord" refers to God's power. His "hand" is metaphorical since the Lord does not have a literal, limited physical body. However, this word picture expresses the Lord's power and judgment, in this context against the evil of Pharaoh.Prior catastrophes were serious (Exodus 7:20–21; 8:3–4, 17, 24). But now the Lord threatens something described as kābēd' m󠅍eōd', literally meaning "massive, very." The words are associated with ideas such as "exceeding," "force," and "abundance." This affliction will be on Egypt's livestock. Egyptian idols such as Hathor and Apis were depicted with features of cattle, or even as deities incarnated into such animals. This plague will be a direct challenge to the power of those gods.
Even more challenging is that the animals belonging to Israel will be spared (Exodus 9:4). This partly explains where the Egyptians obtained the livestock threated by the seventh plague of hail (Exodus 9:19–22). They would have been forced to buy replacements from the Israelites. That Israel's animals would be untouched further emphasizes that the Lord God, not Egyptian idols, are real.