None but a mule denies his family.
— Arabic Proverbs

mules are always boasting that their ancestors were horses.
Proverbs mule quote

A mule will labor ten years willingly and patiently for you, for the privilege of kicking you once.
— William Faulkner

And we never got the mule, let alone the forty acres.
— Charles Evers

If you take a bale of hay and tie it to the tail of a mule and then strike a match and set the bale of hay on fire, and if you then compare the energy expended shortly thereafter by the mule with the energy expended by yourself in the striking of the match, you will understand the concept of amplification.
— mule quotation by William Bradford Shockley