“In preaching the word there is some toil, and this Paul declares when he says, ‘Let the elders that rule well be counted worthy of double honor, especially they who labor in the word and doctrine.’ (1 Tim. v. 17) Yet it is in your power to make this labor light or heavy; for if you reject our words, or if without actually rejecting them you do not show them forth in your works, our toil will be heavy, because we labor uselessly and in vain: while if ye heed them and give proof of it by your works, we shall not even feel the toil, because the fruit produced by our labor will not suffer the greatness of that labor to appear. So that if you would rouse our zeal, and not quench or weaken it, show us, I beseech you, your fruit, that we may behold the fields waving with corn and being supported by hopes of an abundant crop, and reckoning up your riches, may not be slothful in carrying on this good traffic.” 

John Chrysostom, Sermon on John 2:4.