One thing, and only one thing, is necessary for Christian life, righteousness, and freedom. That one thing is the most holy Word of God, the gospel of Christ, as Christ says in John 11[:25],"I am the Resurrection and the life; he who believes in Me, though he die, yet shall he live"; and in John 8[:36],"So if the Son makes you free, you will be free indeed"; and in Matt. 4[:4],"Man shall not live by bread alone, but by every word that proceeds from the mouth of God." Let us then consider it certain and firmly established that the soul can do without anything except the Word of God and that where the Word of God is missing there is no help at all for the soul. If it has the Word of God it is rich and lacks nothing since it is the Word of life, truth, light, peace, righteousness, salvation, joy, liberty, wisdom, power, grace, glory, and of every incalculable blessing. This is why the prophet in the entire Psalm  and in many other places yearns and sighs for the Word of God and uses so many names to describe it.
Martin Luther, Here I Stand