English idiom or proverb equivalent for "saying something, and doing the opposite"

Could somebody please help me by giving an English idiom or proverb used for the people who say something and do exactly opposite

Solution 1:

The sort of person you are describing is called a hypocrite. You could also refer to such a person as a fraud, poser, fake or phony.

It's hard to provide a suitable idiom with the information you provided as we don't know what you are trying to communicate with the idiom. The closest I can think of would be 'pot calling the kettle black'.

Solution 2:

"Do as I say, not as I do."

This is said about a person who says one thing, but does the opposite. For example: - You might say not to lie to your children, but you lie to your friends and family.