John Gill, on 1Cor 9:9

Or saith he it altogether for our sakes,.... That is, God says this, or delivers out this law, forbidding the muzzling the ox, while it treads out the corn; not merely for the sake of the ox, but chiefly for the sake of men; and so Jarchi upon the place says, that the ox is mentioned, , "to express man"; and so another of the Jewish writers (m) interprets the law in Deu 22:6. "Thou shalt not take the dam with the young"; "the intention of the command is, not to have mercy on birds, "but for the sake of men", he (God) says this, whom he would accustom to meekness and compassion:'' and particularly this is here said, for the sake of ministers of the Gospel, who for their spiritual strength, and labours in their work, may be compared to oxen; see Eze 1:10. This law is elsewhere produced by the apostle, and urged in favour of the maintenance of ministers, as here, Ti1 5:17 and therefore for our sakes no doubt it is written; to teach men, that as any workmen are not to be deprived of proper sustenance, so neither they that labour in the word and doctrine: that he that ploweth should plow in hope; of enjoying the fruit of his labours: and that he that thresheth in hope, should be partaker of his hope; of having a supply out of that he is threshing. (m) R. Menuachcm apud Ainsworth on Deut. xxii. 7. & Drusium in loc.