Francois Fenelon was the court preacher for King Louis XIV of France in the 17th century. One Sunday when the king and his attendants arrived at the chapel for the regular service, no one else was there but the preacher.

King Louis demanded, “What does this mean?”

Fenelon replied, “I had published that you would not come to church today, in order that your Majesty might see who serves God in truth and who flatters the king.”

from bible.org