Speak what you are told
The Lord Jesus makes a very important point here. Unless you are steady in prayer (darkness) and steady in the study of the word (what you hear), you shouldn't go out an preach what your heart desires. We are told to preach upon the housetops that which the Lord has spoken unto us. How easy it is to assume that we can say what we want because we "know better". A heart of prayer and discipline Bible study knows God's will and knows what should be said. Only after having these disciplines, can a true warrior stand atop a housetop and boldly proclaim that which comes from God, not from man.
