Luther pleaded with ministers to be diligent in their study. He said:
Some pastors and preachers are lazy and no good. They do not pray; they do not read; they do not search the Scripture… The call is: watch, study, attend to reading. In truth you cannot read too much in Scriptures; and what you read you cannot read too carefully, and what you read carefully you cannot understand too well, and what you understand well you cannot teach too well, and what you teach well you cannot live too well… the devil… the world…and our flesh are raging and raving against us. Therefore, dear sirs and brothers, pastors and preachers, pray, read, study, be diligent… This evil, shameful time is not the season for being lazy, for sleeping and snoring [Quoted in John Piper, The Legacy of Sovereign Joy (Wheaton: Crossway Books, 2000), 101].