All houses become impure from Negaim [diseased patches on skin, clothes, or houses that create impurity] except those of non-Jews. One who buys houses from non-Jews should examine them as if in the beginning [of the Nega]. A round house, a triangular house, or a house built on a ship or on a mast or on four beams, does not become impure from Negaim. If it were square, even if it were on four pillars, it would be able to become impure.

A house that one of its sides is covered in marble, one with rocks, one with bricks and one with dirt is pure. A house that did not have in it stones, wood or dirt and a Nega appeared in it and later they brought into it stones, wood or dirt, it is pure. Similarly a piece of clothing that was not woven [an area of] three by three [fingers], and a Nega appeared on it, and later it was woven to three by three, it is pure. A house does not become impure from Negaim until it has bricks, woods and dirt.

How many stones must be in it?  Rabbi Yishmael says four, Rabbi Akiva says eight, for Rabbi Yishmael used to say [that the Nega does not cause impurity] until it is the size of two beans on two stones or one stone. Rabbi Akiva says, until it is the size of two beans on two stones but not on one stone. Rabbi Elazar ben Rabbi Shimon says, until it is the size of two beans on two stones on two walls in a corner, its length being like two beans and its width being like one bean.

[How much] wood? Enough to put under a lintel. Rabbi Yehuda says, enough to make a "sandal" behind the lintel. Dirt? Enough to put between the cracks. Walls of a trough and partition walls do not become impure from Negaim. Jerusalem and outside of Israel do not become impure from Negaim.

How is a house examined? (Leviticus 14:35) "The one who owns the house comes and tells the priest saying, Something like a Nega has appeared in my house." Even a learned person who knows that it is definitely a Nega, cannot declare and say, "a Nega has appeared in my house," but rather he must say, "Something like a Nega has appeared in my house." (Leviticus 14:36) "The priest commands the house to be emptied (before the priest comes to see the house so that everything in the house will not become impure and then the priest comes to examine the house"). Even bundles of wood and bundles of reeds, says Rabbi Yehuda. Rabbi Shimon says is he being kept busy emptying out his house? Rabbi Meir says, What of his property becomes impure? If you want to say his wooden utensils, his clothing, and his metal objects, he can immerse them and they will become pure. For which items was the Torah concerned? For his earthenware vessels, his small jugs and his oil dropper. If the Torah was so concerned for his less valuable objects, how much more so for his valuable objects. If so for his money, how much more so for the lives of his sons and daughters. If so for what belongs to a wicked person, how much more so for what belongs to a righteous person.

He does not go into his own house to quarantine it, nor does he go inside the house with the Nega and quarantine it. Rather he stands next to the entrance of the house with the Nega in it and quarantines it, as it says "The priest goes out of the house to the entrance of the house and quarantines the house for seven days" (Leviticus 14:38). He comes at the end of the week and examines if it spread. "The priest commands and they remove the stones that have the Nega on them and they send them to the outside of the city to an impure place" (Leviticus 14:42). "And they take other stones and bring them in place of the removed stones and he takes different dirt and plasters the house" (Leviticus 14:42). He does not take stones from one side of it to put in the other side of it nor dirt from one side to place in another side and not lime from any place. He does not bring one in place of two [stones] nor two in place of one, but he can bring two in place of two, in place of three, or in place of four. From here they said, Woe to the evil person, woe to his neighbor. Both remove [the stones], both scrape [around them] and both bring the [new] stones. However, he alone must bring the [new] dirt as it says, "he takes different dirt and plasters the house." His friend does not help with the plastering.

[The priest] returns at the end of the week and he examines: If it returns, "And he destroys the house, its stones, its wood, and all of the dirt of the house, and removes to the outside of the city to an impure place" (Leviticus 14:45). An adjacent spreading [causes impurity] in any amount or [a spreading] from a distance [if it is] the size of a bean, and a returning Nega in houses [if it is] the size of two beans.