פּירוש אויף ויקרא 19:13

“You shall not defraud your fellow” [19:13]. When your fellow works for you, pay him immediately and do not make him run after his pay the next day. You must pay him the same day that he earned it.⁹Rashi, Leviticus, 19:13.

לא תעשק THOU SHALT NOT WRONG [THY FELLOW-MAN] — This refers to one who withholds the wages of a hired servant (Sifra, Kedoshim, Section 2 9; Bava Metzia 61a).

לא תעשוק את דעך, "Do not oppress your fellow Jew." After the Torah had forbidden the acquisition of someone else's money through theft a person might conclude that the Torah's objection is only to thievery and not to other ways of appropriating something which is rightfully someone else's. This is why the Torah had to outlaw the obtaining of money by someone exploiting his position of strength vis-a-vis a person whose social or financial position places him at a disadvantage. The prohibition includes withholding wages of a labourer even only for one night.