Midrasch zu Wajikra 14:43

1) (Vayikra 14:43) ("And if the plague-spot returns and blossoms in the house after he removed the stones and after the house has been scraped and after it has been plastered. (Vayikra 14:44) And the Cohein shall come and he shall see, and, behold, the plague-spot has spread in the house, it is blight leprosy in the house; it is tamei.") "And if the plague-spot returns and blossoms in the house": Just as we speak of a man returning to his place, here, too, the plague-spot returns to the same stones. This tells me only of his place. Whence do we derive the entire house for inclusion? From "in the house." I might think that the size of a garis (makes it subject to tumah); it is, therefore, written here "plague-spot" and before, (Vayikra 14:37), "plague-spot." Just as there, two garisin, here, too, two garisin.

2) "and they shall remove": This teaches us that both of them (i.e., the owner of the affected house and his neighbor, who shares the wall) remove — whence they said "Woe to the wicked one and woe to his neighbor!" Both remove, both scrape (viz. Vayikra 14:41), both bring (new) stones. I might think that if the wall adjoined the atmosphere (of his neighbor's property, but was not common to both of their houses) both of them should do the removal; it is, therefore, written (Vayikra 14:43) "after he removed the stones." How is this to be understood? A wall between him and his neighbor, both remove; a wall adjoining the atmosphere, he himself removes.

2) In sum: Adjacent spreading, any amount; distant (spreading), a garis; returning to houses, two garisin.