John Calvin Commentary Deuteronomy 25:4

"Thou shalt not muzzle the ox when he treadeth out [the grain]." — Deuteronomy 25:4 (ASV)

Thou shalt not muzzle the ox. This passage, indeed, properly belongs to the Supplements of the Commandment, but since it is a confirmation of the preceding decree, it seemed fitting to connect them. This is especially because its faithful expositor, Paul, declares that God had no other purpose in delivering it than that the laborer should not be defrauded of his just wages (1 Corinthians 9:10). For when he is speaking of the maintenance to be provided for the ministers of the Gospel, he adduces it as proof for his case. And, so that no one would object that there is a difference between oxen and men, he adds that God does not care for oxen, but that it was said for the sake of those who labor.

Meanwhile, we must bear in mind that humans are so instructed in equity that they are bound to exercise it even towards animals. For Solomon rightly emphasizes the injustice by which our neighbor is injured, with the comparison: A righteous man regardeth the life of his beast (Proverbs 12:10).

The main point is that we should freely and voluntarily pay what is right, and that everyone should be strict with himself regarding the performance of his duty. For if we are bound to supply subsistence for animals, how much less should we wait for people to persistently ask us for them to receive what they are owed.