He that can toy with his ministry and count it to be like a trade, or like any other profession, was never called of God. But he that has a charge pressing on his heart, and a woe ringing in his ear, and preaches as though he heard the cried of hell behind him, and saw his God looking down on him-oh, how that man entreats the Lord that his hearers may not hear in vain!
Spurgeon at His Best (ed. Baker Publishing Group, 1988)