The problem with which the Rabbis grappled was how could the death penalty which was demanded by the Law be mitigated in the face of the explicit words of the Torah. Commutation of the death sentence by a fine or by wergild could not be considered where the Bible did not specify the option of a ransom (_Kofer_). The Torah expressly prohibits modifying into a fine the death penalty which was the due of the murderer.[113] The Bible furnishes no precedent for commuting the death penalty to one of deportation. Exile involved the banishment of the Jew from the full exercise of Judaism. Herod was condemned for selling law-breakers out of the kingdom. “For slavery to foreigners and such as did not live after the manner of the Jews, and necessity to do whatever such men should command, was an offence against our religion rather than a punishment to such as were found to have offended, such a punishment being avoided in our original laws,”--the Bible.[114] The cities of refuge no longer had asylum power. Exile was considered a more grievous punishment than death by the sword or by starvation and was regarded as harder even than death, itself the hardest of the ten hardest things created in the world.[115] Enslavement to Jews was specified by the Bible as a legitimate punishment only in certain cases.[116] Similarly, both the application and the severity of scourging were limited.[117] Prisons in Jewish antiquity were used usually as a ward house in which the accused was detained until sentence could be pronounced.[118] But sometimes the prison seems to have been used also as a punitive institution.[119] In one instance, the principle of commuting a death penalty to a sentence of life imprisonment is recognised. The Mishna prescribes[120] that when a man has twice committed a crime for which excision is the penalty and he has received the lash twice, on his committing this crime a third time, he is imprisoned and fed on barley until he bursts. Or when one has committed a murder and there are no witnesses to condemn him, he is imprisoned and fed on frugal fare of bread and water.[121] In other words, when a murder has been committed and it is certain that the accused man was the murderer, but owing to legal technicalities,[122] it is impossible legally to prove his guilt; or if the circumstantial evidence is thoroughly convincing,[123] the Rabbis felt that it would be dangerous to society and against all principles of justice to allow such a known murderer to go free. In any of these cases, he should be imprisoned in a den of the height or length of a man and fed in such a manner as to bring about his early death. This seems to be the only passage in Rabbinical literature in which imprisonment is spoken of as a possible mitigation of the immediate death penalty.