For it is written - Deuteronomy 25:4.
In the law of Moses - See the note at Luke 24:44.
Thou shalt not muzzle the mouth ... - To muzzle means, “to bind the mouth; to fasten the mouth to prevent eating or biting” - Webster. This was done either by passing straps around the mouth, or by placing, as is now sometimes done, a small “basket” over the mouth, fastened by straps to the horns of the animal, so as to prevent its eating, but not to impede its breathing freely. This was an instance of the humanity of the laws of Moses. The idea is, that the ox should not be prevented from eating when it was in the midst of food; and that as it labored for its owner, it was entitled to support; and there was a propriety that it should be permitted to partake of the grain which it was threshing.
That treadeth ... - This was one of the common modes of threshing in the east, as it is with us; see the note and illustration on Matthew 3:12.
The corn - The “grain,” of any kind; wheat, rye, barley, etc. Maize, to which we apply the word “corn,” was then unknown; see the note at Matthew 12:1.
Doth God take care for oxen? - Doth God take care for oxen only? Or is not this rather “a principle” which shows God’s care for all that labor, and the humanity and equity of his laws? And if he is so solicitous about the welfare of brutes as to frame an express law in their behalf, is it not to be presumed that the same “principle” of humanity and equity will run through all his dealings and requirements? The apostle does not mean to deny that God does take care for oxen, for the very law was proof that he did; but he means to ask whether it is to be supposed that God would regard the comfort of oxen and not of people also? Whether we are not to suppose that the same principle would apply also to those who labor in the service of God? He uses this passage, therefore, not as originally having reference to people, or to ministers of the gospel, which cannot be; but as establishing a general “principle” in regard to the equity and humanity of the divine laws; and as thus showing that the spirit of the law of God would lead to the conclusion that God intended that the laborer everywhere should have a competent support.