Also see definition of "Muzzle" in Word Study
Muzzle [ebd]
Grain in the East is usually thrashed by the sheaves being spread out on a floor, over which oxen and cattle are driven to and fro, till the grain is trodden out. Moses ordained that the ox was not to be muzzled while thrashing. It was to be allowed to eat both the grain and the straw (Deut. 25:4). (See AGRICULTURE.)
MUZZLE [isbe]
MUZZLE - muz'l (chacam; phimoo) : According to the Deuteronomic injunction (Dt 25:4), the ox was not to be muzzled while treading the grain, i.e. threshing. The muzzle was a guard placed on the mouth of the oxen to prevent them from biting or eating. The threshing ox would have ample opportunity of feeding (compare Hos 10:11). The Deuteronomic injunction is quite in accordance with the humane spirit which inspires it all through. Paul quotes this law in two places (1 Cor 9:9; 1 Tim 5:18) to illustrate his view that the "laborer is worthy of his hire."T. Lewis
Also see definition of "Muzzle" in Word Study
