Spurgeon, from Counsel For Christian Workers:
Let no man be deceived with the idea that if he carries out the right, by God’s grace he will prosper in this world as the consequence. It is very likely that, for a time at least, his conscientiousness will stand in the way of his prosperity.
God does not invariably make the doing of the right to be the means of pecuniary gain to us. On the contrary, it frequently happens that for a time men are great losers by their obedience to Christ.
But the Scripture always speaks as to the long run; it sums up the whole of life [that is, including eternal life] — there it promises true riches. If thou wouldst prosper, keep close to the Word of God, and to they conscience, and thou shalt have the best prosperity.