Dictionary.com
definitions

Practice what you preach

Do yourself what you advise others to do.

The New Dictionary of Cultural Literacy, Third Edition Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Idioms and Phrases with practice what you preach

practice what you preach

Behave as you would have others behave, as in You keep telling us to clean up, but I wish you'd practice what you preach. This idiom expresses an ancient idea but appeared in this precise form only in 1678. Also see do as I say.

The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.