Meaning: someone leading others who have similar limitations. Use examples.
Rewrite 1: the deaf singing to the deaf
Rewrite 2: the mute pontificating to the deaf
Rewrite 3: a glutton giving a pep talk to a dietern2
Rewrite 4: an adulterer promoting monogamy to an adulteress

Comment: You might imagine all the really strange things people with limitations could try to do for others who have equal limitations.

More reading about clichés
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• TV Sitcom Clichés: From “The Web's largest collection of clichés, euphemisms, sayings and figures of speech.”