pot calling the kettle black; people in glass houses shouldn't throw stones
Proverbial expression pointing out hypocrisy: criticizing someone for a fault you share. The literal image is a monkey laughing at another monkey's red buttocks, oblivious to its own.
He scolded me for being late, but since he's often late himself, it's the pot calling the kettle black.
Those two laughing at each other's outfits is really a case of the pot calling the kettle black.
Means 'six of one, half a dozen of the other'; similar in pointing out little difference, but not specifically about hypocrisy.
From the image of a monkey laughing at another monkey's red buttocks, unaware that its own are equally red. The exact origin is uncertain, but it is a traditional Japanese proverb.