When the Law was given on Mount Sinai, the Israelites learned to make various sacrifices for atonement and worship. The blood of animals symbolized a ceremonial or outward cleanness that became spiritually real thanks to Christ’s sacrifice of Himself on the cross for sin (see Heb. 9:11–22). But even before the Law was given, God used the tenth plague to begin to teach His people that “without the shedding of blood there is no forgiveness” (Heb. 9:22). The blood of a lamb, spread on the doorposts of their homes, would mark them for life instead of death. Because of the blood, the angel of death would “pass over” them on that fateful day (Ex. 12:23). Moses boldly announced the tenth plague in the same audience with Pharaoh as when he was told, “Get out of my sight!” (10:28). This plague would be the final one. And it would break Pharaoh’s will, ending the standoff. In this dramatic finale, all the firstborn sons of Egypt, both people and cattle, would die (12:29–30). Only the Israelites would be spared. Such an event would be a family and cultural catastrophe—a judgment to end all judgments. Given that Moses had a perfect track record, Pharaoh should have listened. But as God warned, “Pharaoh will refuse to listen to you—so that my wonders may be multiplied in Egypt” (11:9). God did not send this final plague lightly. According to the Moody Bible Commentary, “The wonders that should have produced humility, repentance, and submission to the word of the Lord yielded a hard heart and culminated in a final, terrible retribution.” Up to this time, Moses hadn’t known exactly when the plagues would end or when deliverance would happen. His growing faith had been open-ended, rooted in the knowledge that God always keeps His promises.