Deuteronomy 25:4

Thou shall not muzzle the ox when he treadeth out [the corn].
] As oxen are used in ploughing, so likewise in treading or beating out the corn; of the manner of which, (See Gill on 1 Corinthians 9:9); now while it was thus employed, it might not be restrained by any means from eating the corn as it had an opportunity, either by a muzzle put over its mouth, or other ways. The Gentiles had several ways of restraining their cattle from eating, while they thus made use of them, to which this law is opposed. Maimonides ^F6 has collected several or them together, as prohibited by it; as putting a thorn into its mouth, causing a lion to lie down by it, or causing its calf to lie down without, or spreading a skin on the top of the corn, that so it may not eat. Aelianus ^F7 relates a very particular way of hindering oxen from eating at such times, used some countries, which was this; that oxen might not eat of the ears of corn, in a floor where they were trod out, they used to besmear their nostrils with cows' dung, which was so disagreeable to the creature, that it would not taste anything though pressed with famine. This law is not to be limited to the ox only, or to this peculiar work assigned it; but, as Jarchi says, respects any sort of cattle, and whatsoever work that has food in it, none of them being to be restrained from eating while at work: and this law was not made for the creatures only, but for men also; and especially for the sake of ministers of the word; who for their strength, labour, and industry, are compared to oxen, and ought to be comfortably supported and maintained on account of their work; for the illustration and confirmation of which this passage is twice produced, (See Gill on 1 Corinthians 9:9); (See Gill on 1 Corinthians 9:10); (See Gill on 1 Timothy 5:17); (See Gill on 1 Timothy 5:18).