Once there was a Caliph of Arabia who hated Jews. So he Issued the following decree: "Every jew who enters my kingdom must be halted by the guards and ordered to tell something about himself. If he lies - he is to be shot. If he tells the truth _ he is to be hanged."

By this stratagem the Caliph hoped to exterminate all the Jews in Arabia, and have some fun while doing it.
One day a Jew came. when the Caliph's servants commanded him to tell something about himself he said, "I am going to be shot today." The guards were confused by his words, so they brought the matter to their royal master's attention.

"Hmmm!" cogitated the wily Caliph. "This is indedd a difficult matter! If we were to shoot the Jew it would imply that he told the truth. In that case the law is that he should be hanged; so I cannot shoot him. Ont the other hand, if I had him hanged it would imply that he told a lie, and for that the law provides shooting; so I cannot hang him."

And so they let him go.