Negaim, Chapter 13, Mishnah 7. Throughout this chapter we have been learning the halachos of tumah that issue from a bayis hamenuga, a house ruled leprous by the kohen, and here the mishnah introduces one more situation: another building, or a tree, extends itself above the leprous house and creates an ohel over it. If a tahor man comes to stand in that shaded area, without ever setting foot inside the leprous house and without laying a hand on it, does he remain tahor?
The picture the mefarshim draw
Visualize the scene. A modest house stands in a certain spot, and a second, larger building has been put up around it and over it, exceeding it in length, in width and in height, so that the small house is entirely enclosed within the large one. That small inner house is the bayis hamenuga. A man now steps into the area that belongs to the outer building and lies beneath its roof, yet he never crosses into the little house inside and never comes into contact with it.
The mishnah's language is "bayis shemeisech," a house that stretches itself out, "al gabei bayis hamenuga," above a leprous house. And the same applies, says the mishnah, to "vechein ilan," a tree, which likewise "shemeisech" spreads out over the leprous house, part of its canopy hanging above the house and part of it hanging beyond, its branches forming an ohel underneath. With the tree, the man is positioned under the portion of the branches that does not extend over the house, so he has not entered any house whatsoever and is only standing beneath a covering. For both scenarios the ruling recorded is "hanichnas lachitzon tahor," whoever comes into the outer space stays tahor, and this is presented as "divrei Rebbi Elazar ben Azaryah."
The reasoning behind his ruling
His opinion is not the accepted halachah, as the mishnah itself will tell us in its final words, yet it calls for explanation, and the Tiferes Yisrael supplies it. Throughout the laws of tumah, and with a meis above all, the objects that contract tumah from sharing an ohel with the source are metaltelin, portable items. Whatever is mechubar, anchored to the ground, stands outside that system. Now a bayis hamenuga is itself the exception, for here we encounter tumah issuing from something that is bound to the earth, a house being immovable by its very nature.
For that reason Rebbi Elazar ben Azaryah confines the exception to its own limits. As the Tiferes Yisrael puts his view, a person contracts this tumah when he actually goes inside the leprous house, or when he remains outside and lays his hand on one of its afflicted stones, for in a bayis musgar even a stone touched from without transmits tumah. In those two instances tumah operates despite the fact that its source is fastened to the ground. But to say that an independent structure that is perfectly tahor in its own right, whether a building or a tree, should link the leprous house and the tahor man by spanning them both is more than he will grant. As long as the afflicted house remains mechubar, planted in the earth, he will not credit it with the power to send tumah through an ohel to a man who never entered it, never touched it, and is standing under an altogether different roof.
The challenge, and the halachah
Now the mishnah brings the dissenting voice: "amar Rebbi Elazar," who argues from two kal vachomer inferences. The first: "mah im even achas," if a single stone, "mimenu," taken from this house, when carried into a tahor house or beneath an ohel already "metamei bevi'ah," transmits tumah to anyone present there simply by their being in that space, then "hu atzmo," the house in its entirety, surely should not be less: shall it be said that it "lo yetamei bevi'ah"? Observe the assumption built into his words: the category of bevi'ah does not require literally stepping indoors; merely finding oneself beneath the covering counts just as much.
His second inference: "umah im even achas," if one afflicted stone that is still set in the wall of the house "metama kol asher ba'ohel," imparts tumah to everything found under its covering, then "habayis kulo," the whole leprous house, when it is "shehu tachas bayis acher," situated under a second building, "lo kol shekein sheyetamei kol mah shebesocho shel chitzon," all the more so should impart tumah to whatever is inside that outer building. The mishnah then rules: "vahalachah k'Rebbi Eliezer," the halachah is with the one who argued against Rebbi Elazar ben Azaryah, so a man who walks into the outer house, or who stands beneath the overhanging branches, becomes tomei.
A remark about the names is in order. The Rav holds that the one who raises these arguments is Rebbi Elazar, and that the "Rebbi Eliezer" of the closing line is nothing more than a printer's error. The shinuyei nuschaos, on the other hand, cite versions in which the name appears as Rebbi Eliezer within the body of the mishnah too, where he is the one who asks whether a house that transmits tumah through a single detached stone should fail to do so in its own right; that seems to have been the girsa in front of the Rav and in front of the Kesef Mishneh. In any event the ruling is not in doubt, and neither is the principle it rests upon: where the tumah of a bayis hamenuga is concerned, standing under a covering that reaches over it is the equivalent of walking in through its doorway.