Pseudo-Luther?

"He is a bad tree and cannot produce good fruit; a dunghill, and can only exhale foul odors. He is so thoroughly corrupted that it is absolutely impossible for him to produce good actions. Sin is his nature; he cannot help committing it."

     Martin Luther, supposedly, though, having expended quite a bit of effort, I doubt it.  The closest we've been able to get so far is that reference to "Werke Wittenberg edition vol III page 518".  Yet that, along with the searchable Past Masters edition of the first 54 volumes of the American edition edited by Pelikan and the searchable edition of the Weimarer Ausgabe (Luthers Werke), as searched (non-exhaustively) by my colleague Robert Smith, of Concordia Theological Seminary, Fort Worth, not to mention Google, the Hathi Trust Digital Library, and so forth, has so far not panned out, as I'll detail here when I get the time.