“You shall not withhold the wages of poor and needy laborers, whether other Israelites or alien who reside in your land in one of your towns. You shall pay them their wages daily before sunset, because they are poor. Their livelihood depends on them. Otherwise they might cry to Yahweh against you, and you would merit guilt.”
Poor laborers were to get their pay immediately every day before sunset. Otherwise guilt would come upon you. This applies both to your fellow Israelites and the resident aliens among you. There is a sense of justice that people who live day to day should get their daily pay.