God made a striking declaration to the Israelites at Sinai: "You have seen what I did to Egypt" (Exodus 19:4). The Mekhilta emphasizes that God was not asking the people to accept a secondhand report. He was not speaking from tradition, not reciting from a written document, not sending messengers, and not producing witnesses to testify on His behalf. The Israelites had witnessed the destruction of Egypt with their own eyes.
This distinction matters enormously in rabbinic thought. Testimony based on direct observation carries a weight that hearsay never can. God pointed to the shared experience of an entire nation — not a private revelation to a single prophet, but a public event visible to millions. Every Israelite who stood at Sinai could confirm what had happened in Egypt because they had lived through it.
The Mekhilta then specifies the sins for which Egypt was punished: idolatry, illicit relations, and the spilling of blood. These are the three cardinal transgressions in Jewish law — the offenses so severe that a person must accept death rather than commit them. Egypt had been guilty of all three, yet God had not exacted punishment immediately. The Egyptians had carried on with their crimes for generations.
Why the delay? The Mekhilta's answer is breathtaking in its directness: God punished Egypt only for the sake of Israel. The timing of divine justice was calibrated not to Egypt's guilt but to Israel's need. The plagues were not simply retribution — they were redemption. Every blow that fell on Egypt was simultaneously an act of liberation for the people who would stand at Sinai and receive the Torah.