Deuteronomy 24:14-15

14Thou shalt not oppress a hired servant [who is] poor and needy of thy brethren, or of thy sojourners who are in thy land within thy gates:

15on his day thou shalt give him his hire, neither shall the sun go down upon it; for he is poor, and his soul yearneth after it; lest he cry against thee to Jehovah, and it be a sin in thee.