See the Structure, "Threshing" for this verse in the book comments for Deuteronomy.
not muzzle. Animals generally muzzled in the East. Compare 1 Corinthians 9:9; 1 Timothy 5:18.
Related Commentaries of Deuteronomy 25:4
Deuteronomy 25:4
4 Thou shalt not muzzle the ox when he treadeth out the corn.