Aesop's Fables (1884)
9. The Dog and the Oyster.
A Dog, used to eating eggs, saw an Oyster, and opening his mouth to its widest extent, swallowed it down with the utmost relish, supposing it to be an egg. Soon afterwards suffering great pain in his stomach, he said: "I deserve all this torment, for my folly in thinking that everything round must be an egg."
Who acts in haste repents at leisure.
Aesop's Fables: A New Revised Version From Original Sources (translator not identified), 1884 . Illustrations by Ernest Henry Griset (1844-1907), John Tenniel (1820-1914) and Harrison Weir (1824-1906). Available online at Project Gutenberg.