The Ass, the Cock, and the Lion

AN ASS and a Cock were in a straw-yard together when a Lion,
desperate from hunger, approached the spot. He was about to
spring upon the Ass, when the Cock (to the sound of whose voice
the Lion, it is said, has a singular aversion) crowed loudly, and
the Lion fled away as fast as he could. The Ass, observing his
trepidation at the mere crowing of a Cock summoned courage to
attack him, and galloped after him for that purpose. He had run
no long distance, when the Lion, turning about, seized him and
tore him to pieces. False confidence often leads into danger. - Aesop

[Source: Aesopfables.com]