Muzzling the Ox
The oxen not muzzled while threshing. Even today the Arab peasant farmer does not muzzle his oxen while they are treading the grain on the threshing floor. He says it would be a great sin to do so.
This agrees with the teaching of the Mosaic Law. "Thou shalt not muzzle the ox when he treadeth out the corn [grain]" (Deuteronomy 25:4). The Apostle Paul quotes this Scripture to enforce his argument that "the laborer is worthy of his hire" (I Corinthians 9:9; I Timothy 5:18).
[Manners And Customs of Bible Lands]