"A great king summoned his wise men. He ordered them, 'Create for me a saying that will stabilize my inner state. When I am unhappy it will bring me joy, and when I am happy it will remind me of sadness. It cannot be too long, as I want to keep it with me always.'
"The wise men consulted and contemplated deeply the king's command. Finally, they returned to the king bearing a small box. In it there was a ring, and inside the ring was inscribed the following words: 'This too shall pass'.

Teaching Stories from Essential Sufism edited by James Fadiman and Robert Frager
found on  www.spiritualityandpractice.com