Avot D'Rabbi Natan 16
When a man stirs up his passion and is about to commit
an act of lewdness, all parts of his body are ready to obey him. On the other
hand, when a man is about to perform an act of piety, all his parts become
laggard, because the impulse to evil in his innards is ruler of the two
hundred and forty-eight parts of his body, whereas the impulse to good is like
a man confined in a prison.