What is the ruling on a person working in polishing marble and engraving it with Quranic verses to sell and place on graves, and is his livelihood lawful?

Writing and engraving Quranic verses on marble should be prohibited due to the risk of exposing them to desecration and harm. The prohibition is further emphasized if the marble is to be placed on graves. Anyone who observes the state to which Quranic verses written on marble in cemeteries devolve—accumulated dust and dirt, and successive rain—will realize that this is a desecration of the Book of Allah the Almighty. Furthermore, the Prophet, peace and blessings be upon him, forbade writing on graves. The sale of these engravings is forbidden according to those who deem the act itself forbidden.