This poem comes into mind when I hear someone preaches with loud voices and fiery words...

I’d rather see a Christian

Than to hear one merely talk,

I’d rather see his actions

And behold his daily walk. —Herrell

quoted form Our Daily Bread, 7th June 2007

Another passage:

Romans 2:21-23 (New International Version)
Copyright © 1973, 1978, 1984 by International Bible Society

21 you, then, who teach others, do you not teach yourself? You who preach against stealing, do you steal? 22 You who say that people should not commit adultery, do you commit adultery? You who abhor idols, do you rob temples? 23 You who brag about the law, do you dishonor God by breaking the law?

quoted form Our Daily Bread, 22nd October 2007