Aesop for Children (1919)
108. THE QUACK TOAD
An old Toad once informed all his neighbors that he was a learned doctor. In fact he could cure anything. The Fox heard the news and hurried to see the Toad. He looked the Toad over very carefully.
"Mr. Toad," he said, "I've been told that you cure anything! But just take a look at yourself, and then try some of your own medicine. If you can cure yourself of that blotchy skin and that rheumatic gait, someone might believe you. Otherwise, I should advise you to try some other profession."
Those who would mend others, should first mend themselves.
Aesop for Children (translator not identified), 1919. Illustrations by Milo Winter (1886-1956). Available online at Project Gutenberg.