John Piper (Martin Luther: Lessons From His Life and Labor)

So he concludes that the true biblical way to study the Bible will be saturated with prayer and self-doubt and God-reliance moment by moment.......Man is powerless to justify himself, powerless to sanctify himself, powerless to study as he ought and powerless to trust God to do anything about this. -John Piper on Martin
Luther (Prayer and Reverent Dependence on the All-Sufficiency of God)

Ref. Martin Luther: Lessons From His Life and Labor