The pot calling the kettle black
The phrase "The pot calling the kettle black" is an idiom used to claim that a person is guilty of the very thing of which they accuse another.
Interpretations and origins
As generally understood, the person accusing (the "pot") is understood to share some quality with the target of their accusation (the "kettle"). The pot is mocking the kettle for a little soot when the pot itself is thoroughly covered in it.
An alternative interpretation, recognized by some, but not all, sources is that the pot is sooty (being placed on a fire), while the kettle is clean and shiny (being placed on coals only), and hence when the pot accuses the kettle of being black, it is the pot’s own sooty reflection that it sees: the pot accuses the kettle of a fault that only the pot has, rather than one that they share.
A poem in an early-twentieth-century school textbook runs:
"Oho!" said the pot to the kettle;
"You are dirty and ugly and black!
Sure no one would think you were metal,
Except when you're given a crack."
"Not so! not so!" kettle said to the pot;
"'Tis your own dirty image you see;
For I am so clean – without blemish or blot –
That your blackness is mirrored in me."—Maxwell's Elementary Grammar, 1904, 
- In Ancient Greece, mention of ‘the Snake and the Crab’ signified much the same idiom. The first instance of this is in a drinking song (skolion) dating from the late 6th or early 5th century BCE. The fable ascribed to Aesop under this name makes the crab an honest actor who kills the snake for the common good. In another, however, concerning a mother crab and its young, the mother tells the child to walk straight and is asked in return to demonstrate how that is done.
- A similar story occurs in the Aramaic version of the story of Ahiqar, dating from about 500 BCE. 'The bramble sent to the pomegranate tree saying, "Wherefore the multitude of thy thorns to him that toucheth thy fruit?" The pomegranate tree answered and said to the bramble, "Thou art all thorns to him that toucheth thee".
- In the Gospel of Matthew 7:3, Jesus is quoted as saying, during the discourse on judgmentalism in the Sermon on the Mount, "Why do you look at the speck of sawdust in your brother's eye and pay no attention to the plank in your own eye?" Many scholars have interpreted this as a proscription against personal attacks in general, not just particulars. In the King James Version of the Bible, it is translated as "And why beholdest thou the mote that is in thy brother's eye, but considerest not the beam that is in thine own eye?"
- A widespread European proverb (see below) whose English equivalent is 'those that live in glass houses should not throw stones' also counsels caution from being judgmental. It appears in the work of Geoffrey Chaucer as 'One who has a glass head should beware of stones' (Troilus and Criseyde II/867–8) and in George Herbert's Outlandish Proverbs (1640) as 'Whose house is of glasse, must not throw stones at another' (#196).
- In his play Troilus and Cressida Shakespeare uses the phrase "The raven chides blackness" to refer to the same phenomenon.
- In Hungarian, the prhase "The owl says to the sparrow its head is big" is used to stress the same point.
- Morris Dictionary of Word and Phrase Origins, by William Morris, Mary Morris
- Brewer’s Dictionary of Phrase and Fable, 1870, revised by Adrian Room (Millennium Edition)
- Pot in Dictionary of Phrase and Fable, by E. Cobham Brewer, 1898 edition
- Francisco Rodríguez Adrados, History of the Graeco-Latin fable I, Brill, Leiden NL 1999, p.146
- Folklore and Fable vol.XVII, New York 1909, p.30
- The Words of Ahiqar: Aramaic proverbs and precepts, Syriac Studies site
- Matthew 7:3–5 "Why do you look at the speck of sawdust...". biblestudytools.com (New International Version).
- Matthew 7:3. biblestudytools.com (King James Version). Retrieved 23 February 2014.
- Simpson, J. A., ed. (1982). "Those who live in GLASS houses shouldn't throw stones". Concise Oxford Dictionary of Proverbs. Oxford University Press. p. 92. ISBN 0-19-281880-5.
- Shakespeare, William. "2:3". Troilus and Cressida. Retrieved 23 February 2014.