The Mekhilta DeRabbi Yishmael states a foundational principle of divine justice: "As one metes it out, so is it meted out to him." God's punishments are not random. They mirror the crime with exacting precision.
The proof comes from the drowning of the Egyptians at the Red Sea. The Egyptians had decreed the death of Israelite babies at the birthstones — the very place where new life entered the world. (Exodus 1:16) records the command to the midwives: "and you see upon the birthstones" — if it is a boy, kill him. The Egyptians turned stones into instruments of death for infants.
So God turned the waters into stones against the Egyptians. When the sea came crashing down on Pharaoh's army, the waters struck them with the force and hardness of stone. The Song at the Sea describes the Egyptians sinking "as a stone" — and the Mekhilta reads this not as a simile but as a measure-for-measure punishment. They killed babies at the stones, so the waters became stones that killed them.
This is midah k'neged midah at its most vivid. The same physical element — stone — appears on both sides of the equation. The birthstones where Egyptian cruelty was enacted become the template for the punishment. The waters did not simply drown the Egyptians; the waters became the very thing the Egyptians had weaponized. God's justice operates like a mirror, reflecting the crime back at the criminal in precise and unmistakable form.