Thou shalt not muzzle the ox when he treadeth out the corn.Deuteronomy 25:4 (KJV)
Muzzle the ox – The Rabbis have long suggested that the word “ox” can apply to all animals that are used for the purpose of work, but clarify that this verse does not apply to humans.
Scripture is speaking of what usually occurs, but the same law applies to any cattle, non-domesticated beast and fowl that are doing some work that is connected with food. But if so why does it (Scripture) state “ox”? To exclude a human being from being subject to this law!Rashi on Deuteronomy
The law applies, of course, also to other animals that can be used to do threshing, It does not apply to human beings, even if these were used for threshing corn, as this is not a normal occupation for which human beings are used.Chizkuni, Rabbi Hezekiah ben Manoah
The claim is that while the Torah states an ox in the verse above, it provides another verse directed toward humans.
24 When thou comest into thy neighbour’s vineyard, then thou mayest eat grapes thy fill at thine own pleasure; but thou shalt not put any in thy vessel.Deuteronomy 23:24-25
25 When thou comest into the standing corn of thy neighbour, then thou mayest pluck the ears with thine hand; but thou shalt not move a sickle unto thy neighbour’s standing corn.
Therefore since it is permitted for a human to eat of their neighbor’s field when entering it, there is no need to relate the muzzling of an ox to a human who works the field. Paul, a rabbi of his time, thought differently.
9 For it is written in the law of Moses, thou shalt not muzzle the mouth of the ox that treadeth out the corn. Doth God take care for oxen?1 Corinthians 9:9-10
10 Or saith he it altogether for our sakes? For our sakes, no doubt, this is written: that he that ploweth should plow in hope; and that he that thresheth in hope should be partaker of his hope.
18 For the scripture saith, thou shalt not muzzle the ox that treadeth out the corn. And, The labourer is worthy of his reward.1 Timothy 5:18
Clearly Paul did not agree entirely with the more recent interpretations of the Rabbis. I’m uncertain if the theology of Paul was accepted during his time in the first century or if the theology was similar to the rabbis I quoted above in later years. Or perhaps the rabbis quoted were actively taking a stance against Paul’s teachings in their own commentary because they viewed Paul a threat. Nevertheless, Paul’s statement is interesting in light of the more recent Jewish commentary.