Wikipedia:Don't call the kettle black

Don't call the kettle black, especially if you yourself are a black pot. The kettle may or may not be black, but attacking it for its blackness will only draw attention to your own blackness, which in turn undermines your position.

The hypocrisy is simply staggering. "Yes, but he started it" is a poor excuse and will not shield you from any of the consequences of your behavior. Just don't do it. Also remember that a mote and a beam are not the same size, and try not to be the beam.

When reminding another user of a policy or guideline regarding behavior, it is well-advised to consider whether you yourself have been following the rule in question. Otherwise, tedious arguments about arguing are likely to ensue.

Users are encouraged to keep a cool head and discuss on talk pages first.

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Wikipedia