"The blows of suffering"

There is an animal called the porcupine that becomes large and fat if
you beat it with a stick.
The more you beat it, the more it thrives, growing fat on the blows
of the stick.
The believer's spirit is in truth a porcupine, for the blows of
suffering make it large and fat,
That is why the suffering and tribulation inflicted upon the prophets
is greater than that inflicted upon the world's creatures.

-- Mathnawi IV: 97-100
Translation by William C. Chittick
"The Sufi Path of Love"
SUNY Press, Albany, 1983

The media:
http://shorl.com/humabiteprade

"The blows of suffering"