John Calvin Commentary James 5:4

"Behold, the hire of the laborers who mowed your fields, which is of you kept back by fraud, crieth out: and the cries of them that reaped have entered into the ears of the Lord of Sabaoth." — James 5:4 (ASV)

Behold, the hire. He now condemns cruelty, the invariable companion of avarice. But he refers only to one kind, which, above all others, ought justly to be considered odious.

For if a humane and just man, as Solomon says in Proverbs 12:10, cares for the life of his animal, it is a monstrous barbarity when a person feels no pity for the one whose sweat they have used for their own benefit. Therefore, the Lord has strictly forbidden in the Law that the wages of the laborer should be withheld overnight (Deuteronomy 24:15).

Moreover, James does not refer to laborers in general, but, for greater emphasis, he mentions farmers and reapers. For what can be more despicable than that those who supply us with bread by their labor should suffer from want? And yet this monstrous thing is common, for there are many with such a tyrannical disposition that they think the rest of humankind exist only for their benefit.

But he says that this wage crieth, for whatever people retain by fraud or violence of what belongs to someone else, it calls for vengeance as if by a loud voice. We should note what he adds: that the cries of the poor reach the ears of God, so that we may know that the wrong done to them will not go unpunished.

Therefore, those who are oppressed by the unjust should endure their sufferings with resignation, because they will have God as their defender. And those who have the power to do wrong should abstain from injustice, so that they do not provoke God against themselves, who is the protector and patron of the poor. For this reason also, he calls God the Lord of Sabaoth, or of hosts, thus indicating His power and His might, by which He renders His judgment more dreadful.