"Believe it, brethren, God never saved any man for being a preacher, nor because he was an able preacher; but because he was a justified, sanctified man, and consequently faithful in his Master's work. Take heed, therefore, to ourselves first, that you be that which you persuade your hearers to be, and believe that which you persuade them to believe, and heartily entertain that Savior whom you offer to them. He that bade you love your neighbors as yourselves, did imply that you should love yourselves, and not hate and destroy yourselves and them." - Richard Baxter, (1615 - 1691; from The Reformed Pastor)
Recommended reading:
A Quest for Godliness - The Puritan Vision of the Christian Life, by J. I. Packer