Deuteronomy 25:4
3 The judge may sentence him to 40 blows, but no more. If he is struck with more than these, you might view your fellow Israelite with contempt. 4 You must not muzzle your ox when it is treading grain. 5 If brothers live together and one of them dies without having a son, the dead man’s wife must not remarry someone outside the family. Instead, her late husband’s brother must go to her, marry her, and perform the duty of a brother-in-law.
1 Corinthians 9:9
7 Who ever serves in the army at his own expense? Who plants a vineyard and does not eat its fruit? Who tends a flock and does not consume its milk? 8 Am I saying these things only on the basis of common sense, or does the law not say this as well? 9 For it is written in the law of Moses, “Do not muzzle an ox while it is treading out the grain.” God is not concerned here about oxen, is he? 10 Or is he not surely speaking for our benefit? It was written for us, because the one plowing and threshing ought to work in hope of enjoying the harvest. 11 If we sowed spiritual blessings among you, is it too much to reap material things from you?
Notes and References
"... When Paul interprets ‘Do not muzzle the ox while threshing’ as ‘do not neglect to pay Christian ministers’ commentators have quite naturally assumed that his exegesis was allegorical. However, comparisons with contemporary rabbinic exegesis suggest that this would have been regarded as a literal interpretation of the plain meaning of the text. Even commentators who have wished to rid Paul of all allegory have concluded that here Paul does use allegory ... Kaiser however does claim that Paul’s interpretation is literal. He says that Paul did not ‘resort’ to allegory, because his interpretation was already implicit in Deuteronomy 25:4, 10 though he too fails to present Paul’s methodology. Unlike Kaiser, I would not regard it as a ‘crisis in exegesis’ if Paul did employ allegory. Allegory was a useful tool in the hands of many early Christian commentators because their congregations and opponents alike understood and accepted this method of argument. ..."
Instone-Brewer, David 1 Corinthians 9.9–11: A Literal Interpretation of 'Do not Muzzle the Ox' (pp. 554-565) New Testament Studies, 38(4), 1992