Deuteronomy 25:4

Thou shalt not muzzle the ox, etc. - In Judea, as well as in Egypt, Greece, and Italy, they make use of beeves to tread out the corn; and Dr. Shaw tells us that the people of Barbary continue to tread out their corn after the custom of the East. Instead of beeves they frequently made use of mules and horses, by tying by the neck three or four in like manner together, and whipping them afterwards round about the nedders, as they call the treading floors, (the Libycae areae Hor), where the sheaves lie open and expanded, in the same manner as they are placed and prepared with us for threshing. This indeed is a much quicker way than ours, though less cleanly, for as it is performed in the open air, (Hosea 13:3), upon any round level plot of ground, daubed over with cow's dung to prevent as much as possible the earth, sand, or gravel from rising; a great quantity of them all, notwithstanding this precaution, must unavoidably be taken up with the grain, at the same time that the straw, which is their chief and only fodder, is hereby shattered to pieces; a circumstance very pertinently alluded to in 2 Kings 13:7, where the king of Syria is said to have made the Israelites like the dust by threshing - Travels, p. 138. While the oxen were at work some muzzled their mouths to hinder them from eating the corn, which Moses here forbids, instructing the people by this symbolical precept to be kind to their servants and laborers, but especially to those who ministered to them in holy things; so St. Paul applies it 1 Corinthians 9:9, etc.; 1 Timothy 5:18. Le Clerc considers the injunction as wholly symbolical; and perhaps in this view it was intended to confirm the laws enjoined in the fourteenth and fifteenth verses of the former chapter. See Dodd and Shaw.

In Bengal, where the same mode of treading cut the corn is used, some muzzle the ox, and others do not, according to the disposition of the farmer - Ward.

Compare the marginal references. In other kinds of labor the oxen were usually muzzled. When driven to and fro over the threshing-floor in order to stamp out the grain from the chaff, they were to be allowed to partake of the fruits of their labors.

25:4 He treadeth out the corn - Which they did in those parts, either immediately by their hoofs on by drawing carts or other instruments over the corn. Hereby God taught them humanity, even to their beasts that served them, and much more to their servants or other men who laboured for them, especially to their ministers, 9:9 .