The tie.
An Arab, desperate for water, was plodding through the desert when he
saw something far off in the distance. Hoping to find water, he walked
toward the object, only to find a little old Jewish man sitting at a card
table with neckties laid out on it.

The Arab said, "My thirst is killing me. Please, do you have water?"
The Jew replied, "I have no water. Would you like to buy a tie?
They are only $150. This one goes very nicely with your robe.
 
"The Arab shouted, "Idiot! I do not need your overpriced tie. I
need water!"
 
"OK," said the old Jew, "it does not matter that you do not want to
buy a tie. I will show you that you have not offended me. If you walk 
over that hill to the East for about four miles, you will find a lovely
restaurant.  Go! Walk that way! The restaurant has all the water you
need!"
 
The Arab staggered away toward the hill and disappeared.
Eight hours later the Arab came crawling back to the Jewish man's
table.
 
The Jew said, "I told you, the restaurant with the water is about
four miles over that hill. Could you not find it?"
 
"I found it," rasped the Arab. "But your brother wouldn't let me in
without a tie!"