Jamieson, Fausset and Brown on Deuteronomy 24:14-15

14-15. Thou shalt not oppress an hired servant that is poor and needy--Hired servants in the East are paid at the close of the day; and for a master to defraud the laborer of his hire, or to withhold it wrongfully for a night, might have subjected a poor man with his family to suffering and was therefore an injustice to be avoided (Le 19:13).