look who's talking
You're in no position to criticize, as in I wish Kate would be on time for once.—You do? Look who's talking! This colloquial idiom dates from the mid-1900s, although another version, you can't talk, is a century or so older.
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.