The following quote is taken from the book, Martin Luther: Selections from his writings edited and with an introduction by John Dillenberger (Preface to the New Testament):
“In sum: the gospel and the first epistle of St. John, St. Paul’s epistles, especially those to the Romans, Galatians, and Ephesians; and St. Peter’s first epistle are the books which show Christ to you. They teach everything you need to know for your salvation, even if you were never to see or hear any other book or hear any other teaching. In comparison with these, the epistle of James is an epistle full of straw, because it contains nothing evangelical. But more about this in the other Prefaces” (Martin Luther, p. 19).
Found on page 14 of Dillenberger’s Martin Luther is the following (referring to the Luther quote above):
Reprinted by permission of the publisher from The Reformation Writings of Martin Luther, volume II, The Spirit of the Protestant Reformation, translated and edited by Bertram Lee Woolf (London: Lutterworth Press, 1956), pp. 278-83.
Martin Luther — that suppositious sot — saith that the epistle of James is spurious and in the Scripture canon it belongeth not.