1 Corinthians 9:10

Or saith he it altogether for our sakes? For our sakes, no doubt, this is written: that he that ploweth should plow in hope; and that he that thresheth in hope should be partaker of his hope. (KJV)

Then: In a continuation of the application from verse 9, Paul adds that the farmer who plows and threshes does so with the hope of enjoying a great harvest. Fee (p. 409)adds that the expectation of harvest applies to the apostles' expectation and right of receipt of material reward from their work.

Now: Baker (p. 132) - The truth of scripture continues to speak across the ages to new situations and new cultures. Paul's genius is that he could do that in the first century.

Extra source: The First Epistle to the Corinthians by Gordon D. Fee (Eerdman's 1987) online http://books.google.com/books?id=XlBp10nUTXAC&dq=Gordon+Fee+Bible+commentator&printsec=frontcover&source=in&hl=en&ei=SwLNSu3nA4v6Mf2XlDo&sa=X&oi=book_result&ct=result&resnum=12#v=onepage&q=&f=falseCornerstone Biblical Commentary 1Corinthians (William Baker), 2 Corinthians (Ralph Martin & Carl Toney), ed. by Philip Comfort. Carol Stream: Tyndale House Publishers, c2006.