. Wood — enough to build a threshold. R’ Yehudah says: Enough to make a ‘‘sandal’’ behind the threshold. Clay — enough to put between the cracks. Walls of a feeding trough and partition walls do not become tamei from negaim. Jerusalem and outside the Land [of Israel] do not become tamei from negaim.

[The Kohen] does not go into his [own] house to confine, nor [does he stand] inside the house that contains the nega to confine. Rather, he stands next to the entrance of the house that contains the nega and confines, as stated: ‘‘And the Kohen shall leave the house to the entrance of the house, and he shall confine the house for seven days.’’ He returns at the end of the week and examines [the house]. If it spread, ‘‘and the Kohen commands that they remove the stones that have the nega and throw them outside the city to a tamei place. And they shall take other stones to replace the [removed] stones, and he shall take other clay and plaster the house.’’ He does not take stones from this side [of the house] and build them into the other side; nor [does he take] clay from this side and build [it] into the other side, nor [does he take] lime. Two [stones] are not replaced with one [stone], nor one [stone] with two, but two, three, or four [stones] can be replaced with two. From here they said: ‘‘Woe is to the evildoer and woe is to his neighbor.’’ Both [owners] remove [the afflicted stones], scrape [around them], and place the [new] stones. However, he alone brings clay, as it is stated: ‘‘And he shall take other clay and plaster the house.’’ His neighbor does not assist him in the plastering.