לֹֽא־תַעֲשֹׁ֥ק אֶת־רֵֽעֲךָ֖ וְלֹ֣א תִגְזֹ֑ל לֹֽא־תָלִ֞ין פְּעֻלַּ֥ת שָׂכִ֛יר אִתְּךָ֖ עַד־בֹּֽקֶר׃
Thou shalt not oppress thy neighbour, nor rob him; the wages of a hired servant shall not abide with thee all night until the morning.
Rashi on Leviticus
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).
Or HaChaim on Leviticus
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.
Rashbam on Leviticus
לא תעשוק, withholding wages and suppressing just claims by converts.