In this passage, God gives Moses and Aaron a specific task as part of the series of plagues sent to persuade Pharaoh to release the Israelites from slavery. The act of taking soot from a furnace and tossing it into the air is symbolic. It represents God's power to transform something as mundane as soot into a tool of divine judgment. This plague, which follows, is a direct challenge to Pharaoh's authority and the Egyptian gods, demonstrating that the God of Israel is supreme.
The use of soot, which is associated with fire and industry, may also symbolize the labor and suffering of the Israelites in Egypt, as they were forced to work in harsh conditions. By using this soot to bring about a plague, God is turning the tools of oppression into instruments of liberation. This act underscores the theme of justice and deliverance that runs throughout the Exodus narrative. It serves as a reminder to all believers of God's power to bring about change and liberation, even from the most oppressive circumstances.