Parashas Behar · Aliyah 1 · Passuk 25:03
Chabad.org — English translation + Rashi
Torah Temimah cites Yerushalmi Kilayim 8:1.
English: “Six years you shall sow.” It was taught: Rabbi Yochanan said: One who plows in the Shemittah year does not receive lashes. What is the reason? Because it is written “six years you shall sow” — and not in the seventh — and “six years you shall prune” — and not in the seventh; and any lav that comes by implication from an aseh is treated as an aseh.
Classical derasha (Yerushalmi) — lav haba miklal aseh.
One who plows in the Shemittah year does not receive the punishment of lashes, because the prohibition is derived from a positive commandment; a lav that comes by implication from an aseh is treated as an aseh.