John Gill 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 of the labourers, who have reaped down
your fields
The wages agreed for by the day, with the labourers in their fields, particularly their reapers; which one instance serves for many others. It is mentioned rather because reaping is a laborious work, and those who are employed in it have nothing to live upon but their hand labour; and especially because they are made use of in cutting down the corn when it is fully ripe, and in great plenty; therefore, to detain their just wages from them argues great inhumanity and wickedness; and yet this was what was done by rich men:

which is of you kept back by fraud, cries ;
to God for vengeance, as the blood of Abel did; and shows that such an evil, however privately and fraudulently it may be done, will be made public, and is a crying one:

and the cries of them who have reaped are entered into the ears of
the Lord of sabaoth ;
that is, the Lord of hosts; of angels, and of men; of the host of heaven, and of the inhabitants of the earth; of Jews and Gentiles, and of rich and poor; and who has power to vindicate the cause of the latter against their rich oppressors, and will do it; his ears are open to their cries, he takes notice of them, and regards them, and will take vengeance on those that injure them. The reference is to (Deuteronomy 24:15) .