Or HaChaim on Exodus 23:12/אור החיים על שמות כ״ג:י״ב

1 תעשה מעשיך, "you shall do your work, etc." The Torah was careful not to write: "all your work" as in the Ten Commandments (concerning the Sabbath). The reason is that during the Shmittah year the farmer cannot do his regular work even on the six days of the week.