"Luther's strength lay in the way in which he laid the burden of the Reformation upon the Lord. Continually in prayer he pleaded, 'Lord, this is thy cause, not mine. Therefore do thine own work; for if this gospel do not prosper, it will not be Luther alone who will be a loser, but thine own name will be dishonored.'" Spurgeon's Sermon Notes
Further recommended reading & listening:
The Best of The Daily Spurgeon
The Forgotten Spurgeon, by Iain Murray
A Defense of Calvinism - by Charles Spurgeon