A.T. Robertson Commentary 1 Corinthians 9:10

"or saith he it assuredly for our sake? Yea, for our sake it was written: because he that ploweth ought to plow in hope, and he that thresheth, [to thresh] in hope of partaking." — 1 Corinthians 9:10 (ASV)

He that plougheth (ο αροτριων). Late verb αροτριαω, to plough, for the old αροω from αροτρον (plough), in LXX and rare in papyri.

In hope of partaking (επ' ελπιδ του μετεχειν). The infinitive αλοαιν is not repeated nor is οφειλε though it is understood, "He that thresheth ought to thresh in hope of partaking." He that ploughs hardly refers to the ox at the plough as he that threshes does. The point is that all the workers (beast or man) share in the fruit of the toil.