Many of you sang very prettily just now, didn't you? I wonder whether you would sing very prettily, if there were a stake or two in Smithfield for all of you who dared to do it? If you sang under pain and penalty, that would show your heart to be in your song. We can all sing very nicely indeed when every body else sings. It is the easiest thing in the world to open your mouth, and let the words come out; but when the devil puts his hand over your mouth, can you sing then? Can you say, "Though he slay me, yet will I trust in him?" That is hearty singing; that is real song that springs up in the night. The nightingale singeth most sweetly because she singeth in the night.
~ CH Spurgeon Songs in the Night