The Mekhilta, the tannaitic midrash on Exodus, addresses a question that cuts to the heart of the Passover story: who actually killed the firstborn of Egypt? The verse states simply: "And the Lord smote every firstborn" (Exodus 12:29). But the rabbis consider an alternative — perhaps God delegated the task. Perhaps an angel carried out the slaughter, or some other celestial emissary.
The Mekhilta rejects this possibility with force. It points to an earlier verse where God Himself declared: "And I shall smite every firstborn" (Exodus 12:12). The emphasis falls on the word "I." Not an angel. Not an emissary. Not a destroying force sent at a distance. God Himself.
This is one of the most theologically distinctive claims in the entire Exodus narrative. In many of the Torah's other interventions — the destruction of Sodom, the battles in the wilderness, the plague of serpents — God works through intermediaries. Angels deliver messages. Natural forces execute judgments. But the tenth plague was different.
On the night of the firstborn, God passed through Egypt personally. No delegation, no chain of command, no buffer between the Divine and the human world. The Mekhilta insists on this point because it defines what made the Exodus unique among all of God's acts in history. He came Himself. That is what made it the night above all nights.