The poor Jewish tailor is beside himself with worry. His wife is very ill and he wants the best doctor in town to treat her. But the doctor is somewhat reluctant because the tailor is so poor and, it being unlikely that his wife could be saved, the tailor might not pay him should his wife die. However, the tailor promises he will pay anything, no matter whether the doctor cures his wife or kills her !
This is sufficient for the doctor and he agrees.

Unfortunately, the doctor cannot save her and the tailors wife dies.

However, when the doctors bill arrives the tailor refuses to pay it despite his promise. After much argument, the doctor and the tailor agree to let the Rabbi decide the case since they both are, after all, Jewish.

The doctor puts his case to the Rabbi that the tailor promised to pay "no matter whether the doctor cured his wife or killed her".

After much thought the Rabbi asks the doctor, "Did you cure her?" "No" admitted the doctor.

"And did you kill her?" "I certainly did not," expostulated the doctor.

"In that case," said the Rabbi, "the tailor has no case to answer because you fulfilled neither of the conditions on which you agreed that the fee should be paid."