Worship, The Missing Jewel of the Evangelical Church by A W Tozer and published by Classics.
A. W. Tozer defines what real worship is all about. "I want to speak of some kinds of worship that God has ruled out. There's no use trying to be nice about it. The kingdom of God has suffered a great deal of harm from fighters - men who would rather fight than pray; but the kingdom of God has also been done great harm by men who would rather be nice than be right. I believe that God wants us to be right, though He wants us to be right lovingly." - A. W. Tozer "If there is no fear of God in our hearts, there can be no worship of God."