English: “Now I know” — until now he had not fully conceded the matter. “For in the very matter in which they dealt wickedly with them” — by the water with which they planned to destroy them, by that same water they themselves were destroyed.
On the daf / in context: See the cited source for the full section.
Type of Learning
Derash on the verse.
What Is Learned
Yisro’s recognition of Hashem’s superiority crystallizes at the sight of measure-for-measure justice: the Egyptians who sought to destroy Yisrael by water were themselves destroyed by water.