Mishnà su Levitico 14:40

[The priest] must not go into his own house to isolate it, nor may he stand within the house in which there is a nega. Rather, he must stand at the door of the house in which is there is a nega, and isolate it from there, as it is said, "The priest shall come out of the house to the entrance of the house, and close up the house for seven days" (Leviticus 14:38). He comes again at the end of the week and inspects the sign to see if it spread. "The priest shall order the stones with the plague in them to be pulled out and cast outside the city into an unclean place" (v.. "They shall take other stones and replace those stones with them, and take other dirt and plaster the house" (v.. He must not take stones from the one side and bring them to the other; nor earth from the one side and bring it to the other; nor lime from anywhere. He must not bring one stone to replace two, nor two to replace one. But he can bring two to replace two or to replace three or to replace four. From here they have said: Woe to the wicked, woe to his neighbor. Both must take out the stones, both must scrape the walls, and both must bring the new stones. He alone, however, brings the earth, as it is said, "And he shall take other coating and plaster the house." His neighbor need not join with him in the plastering.

In the case of a stone in a corner, when the stone is taken out it, he must take it all out; But when [the house is] torn down he tears down his own [part] and leaves that which belongs to his neighbor. Thus it follows that there is a greater stringency for taking out than for tearing down. Rabbi Elazar says: if a house is built of rows of head stones and small stones, and a nega appears on a head stone, all of it must be taken out; but if it appeared on the small stones, he takes out his stones and leaves the others.