כלי יקר — כל המצוה אשר אנכי מצוך היום תשמרון לעשות

Q — Why does the verse begin in singular — 'אשר אנכי מצוך' — but pivot mid-sentence to plural — 'תשמרון... תחיון... ורביתם'?

A — Kli Yakar grounds the shift in the Rambam (Hilchot Teshuvah 3:4) and Kiddushin 40b: a single mitzvah by a single person 'הכריע את עצמו ואת כל העולם לכף זכות.' The Torah's grammar enacts this: the command speaks to the individual ('מצוך' — singular), but its consequences flow to the many ('תחיון... ורביתם' — plural). The single mitzvah of the יחיד is reckoned as if רבים had performed it. The shift in number is the metaphysics of merit made visible in syntax. Kli Yakar adds a second nuance: 'כל *המצוה*' (singular) — even one mitzvah, properly kept, earns 'למען תחיון.' Salvation depends on getting even one mitzvah right.