Put your money where your mouth is

Put your money where your mouth is - to show by your action and not just by your words that you support or believe in something.

Example - "If you are really interested in helping the homeless, you should put your money where your mouth is."

Image - http://www.mykrobinson.com/wp-content/uploads/2013/03/put-your-money-where-your-mouth-is.jpg