A portion of a letter written by Robert Murray McCheyne to Rev. Dan Edwards, who was on his way to Germany as a missionary. The letter was written on October 2, 1840:
I trust you will have a pleasant and profitable time in Germany. I know you will apply hard to German; but do not forget the culture of the inner man—I mean of the heart. How diligently the cavalry officer keeps his saber clean and sharp; every stain he rubs off with the greatest care. Remember you are God’s sword, His instrument—I trust a chosen vessel unto Him to bear His name. In great measure, according to the purity and perfections of the instrument, will be the success. It is not great talents God blesses so much as great likeness to Jesus. A holy minister is an awful weapon in the hand of God.
Robert Murray M’Cheyne: Memoir and Remains, Andrew A. Bonar, first published in 1884, reprinted by the Banner of Truth, 1966, p. 282.