"The houses of Jerusalem do not become defiled through nega'im" (Baba Kama 82b).
The Talmud explains that the houses in Jerusalem were not subject to the leprous spots described in this week's parasha because, as the Torah says (14:34), "And I will bring the plague of leprosy in the house of the land of your possession." Only a house on land parceled out to one of the tribes is subject to this affliction. But since Jerusalem was not divided among the tribes, its houses were impervious to this form of punishment.
What difference does it make whether Jerusalem belonged to an individual tribe or to all the tribes of Israel? If its inhabitants deserved tzara'at on their houses, they should have been afflicted with it.
Perhaps the Torah is telling us something about the power of unity. It is not that Jerusalem did not belong to any individual tribe, but that it belonged to all the tribes. It was everyone's capitol and everyone had a right to it and an obligation. The obligation was to preserve the unity of Jerusalem; to keep it whole and undivided; to buttress the achdut, the oneness and spiritual focus upon which the rest of the nation could build.
An individual might have deserved the terrible affliction of tzara'at, but the power of the klal, the fact that all of the tribes gave a part of themselves to this city, was sufficient merit to counter personal sin, even something as serious as speaking evil.
If only we could all give a little of ourselves to Jerusalem, then no affliction in heaven or on earth would be able to taint its glory or disturb the "peace of Jerusalem."
Yaacov Peterseil is a publisher and author, and the proud owner of a home in Jerusalem.