Leaving Eretz Yisroel

The Gemora (Daf Yomi: Nazir Daf 55a) cited a braisa: If one enters the land of the nations inside of a carriage, chest or closet, Rebbe rules that he is tamei and Rabbi Yosi the son of Rabbi Yehudah holds that he is tahor.

The Gemora suggested that the basis for their argument is as follows: Rabbi Yosi the son of Rabbi Yehudah holds that since traveling inside a chest is uncommon, the Rabbis did not intend for the decree to apply in such a situation. Rebbe holds that although it is unusual, the Rabbis decreed tumah in this case as well.

The question is asked: How can this be their argument? Do we not find all throughout Gemora that the Rabbis did not intend that their decree should be applicable in cases that are uncommon? We do not find any Tanna that disagrees with this principle! Why in this specific case would they dispute this well-established principle?

The Mishna L’melech answers: In this case, the Rabbis decreed a tumah on anyone entering the land of the nations, even if they enter in an unusual manner. This is because they wished to prevent people from leaving Eretz Yisroel. Their original decree was on all situations!