Mishneh Torah — Positive Mitzvot מצוות עשה, Chapter 200
The full Hebrew text of Mishneh Torah, Positive Mitzvot, Chapter 200, with English translation by Maimonides (Rambam).
ליתן שכר שכיר בזמנו, שנאמר: "ביומו תיתן שכרו" (דברים כד,טו).
To pay a worker his wage on time, as [Deuteronomy 24:15] states: "Pay him his wage on the day it is due."