Blessed is he whose members and arms thus serve God. Yes, if someone knows that the power and wisdom of God are of such a sort, he trusts wholly, not in the mask of God but in the Word behind the mask; and he can and does perform wonders, yes, everything, in the Lord. So it will come about that he walks on, free and safe in the midst of presumption and despair, and does not tempt God while he has what he needs; again, he does not despair if what he needs is lacking. For God, who works with him under the things which he has, will also work with him without these things, where he has nothing. Thus he does not have an abundance or have more when everything is at hand, nor does he suffer want or have less when everything is lacking. For in both situations he has God, just as Paul says (Phil. 4:12): “I have learned to abound, I have learned to endure want.” The godless, however, are puffed up by the property that is on hand; and when this is gone, they are downcast, because they grasp only the mask of things. Others are groping, because they do not want to use what has been given.
Luther’s works, vol. 9: Lectures on Deuteronomy 1525