the act of doing something that you proclaim as truth yet you turn around and do it yourself.
hypocrisy at its finest.

bait and switch but when accused you use the excuse "i was there to preach"
perfect example stay off facebook but i am on twitter.

Preach;

to have somebody speak up about a subject with an opinion that is very common and isn’t afraid to repeat it (they’re a preach)

An anus after church.

An unsolicited message explaining your error and the consequences of said error.

Advocate to someone an opinion or stance that s/he already holds -- preach to the converted -- push on an open door . . . with a flavour of "a bit of a waste of time and effort"

Textbook preaching occurs when a teacher (usually a supply/cover teacher who is relatively inexperienced) teaches pupils by relying solely on the contents of whichever textbook relates to her current lesson (e.g. a teacher covering in Chemistry reading verbatim from a chemistry textbook)
More often than not, this method does absolutely nothing to help students learn, other than reinforcing already-negative attitudes about supply teachers and forcing pupils to seek out their own means of learning.
The only exceptions include teachers assigning tasks from the textbook or simply asking students to read extracts.

Another way to say I agree