This is assuredly the greatest and heaviest cross, and truly shameful pay is given to Joseph for the services he has performed most faithfully for 18 years. Not only his labors but also his virtues are paid for with punishment and a most disgraceful death. Now let him serve who wants to serve the world, for no servant except the devil and his mother belongs in the world.51 Joseph had managed the property and the house of his master with the greatest readiness and faithfulness, but this harlot gives him the very worst thanks. Therefore let the saints expect no other reward from the world, and let them not think that they should show faithfulness and constancy in office for the sake of the world. For the world does not deserve being served with even one little finger; what it deserves is that the devil with all his angels should rule over it. This he certainly does in a horrible way. But, as Paul says: “The creature has been subjected to futility, but for the sake of Him who subjected it” (Rom. 8:20). In great part we serve, teach, admonish, suffer, give consolation, and do the things commanded by God for unworthy men. Here we gain nothing for our services but hatred, envy, and exile; and our whole life is nothing else than the loss of kindnesses.
Therefore you must never hope that the world will acknowledge and remunerate your faithfulness and diligence; for it does the opposite, as this example attests. Set another goal, therefore, for your service and your life than the thanks of the world. Its gratitude is suddenly changed into fury. Reflect as follows: “If I am a pastor or the director of the studies of young people or in any other position, I shall perform my duty diligently, not because I am expecting some reward from those whom I serve—for I am simply giving up all hope of gratitude—but I shall imitate the kindness of my heavenly Father, who scatters His blessings, gives gold, silver, fruits, peace, and good health even to the unthankful and the worst men. And I shall be mindful of the admonition of Christ, who says: ‘You, therefore, must be perfect, as your heavenly Father is perfect’ (Matt. 5:48); that is, serve even the wicked, the unworthy, and the unthankful, and not only the worthy, the thankful, and the good.” There will be a few who will make acknowledgment and be grateful. The rest will even plot against your life. Thus Joseph’s example teaches what is to be expected in return for the greatest of benefits: certainly bonds and imprisonment.
Luther’s works, vol. 7: Lectures on Genesis: Chapters 38-44 p 96-97