By Rabbi Yirmiyohu Kaganoff (Rabbi Kaganoff.com)
In Parshas Ki Seitzei, the Torah instructs “Beyomo sitein secharo velo sa’avor alav hashemesh,” “On that day (that is, the day the work was completed) you should pay his wage, and the sun shall not set (without him receiving his payment)” (Devarim 24:15). The Torah mentions two mitzvos; a positive mitzvah (mitzvas aseh) and a negative mitzvah (lo sa’aseh) to guarantee that a worker is paid before sunset of the day that he performed his job. Thus, someone who pays his worker on time fulfills a positive mitzvah, whereas if he neglects to pay him on time and the worker demands payment, he has trangressed a lo sa’aseh.