Once upon a time, it happened that Mullah Nasruddin was in need of some money.  Therefore he carefully combed his beard, put on his largest and most impressive turban, and set up a stall at the side of the market-place, with a sign that read, “Spiritual Advice for Sale”.

After a time, a passer-by stopped there, curious about this novelty, and asked the Mullah what sort of spiritual advice he was offering.

“Some things must be paid for in advance,” said the Mullah, doing his best to look wise.

“But what if I don’t like the advice?” asked the man.

“In that case, you can return it.”

“And my money?”

“A good point, friend,” replied Nasruddin. “I believe in fair and honest trade. If I don’t like your money, I agree to return it, too.”