“If you are a craftsman you will find the Bible placed in your workshop, in your hands, in your heart; it teaches and preaches how you ought to treat your neighbor. Only look at your tools, your needle, your thimble, your beer barrel, your articles of trade, your scales, your measures, and you will find this saying written on them. You will not be able to look anywhere where it does not strike your eyes. None of these things with which you deal daily are too trifling to tell you this incessantly, if you are but willing to hear it; and there is no lack of such preaching, for you have as many preachers as there are transactions, commodities, tools, and other implements in your house and estate; and they shout this to your face, ‘My dear, use me toward your neighbor as you would want him to act toward you with that which is his.'”
Again, this is Luther, according to Gustaf Wingren in Luther on Vocation.