Leviticus 14:38

Then the priest shall command that they empty the house, before the priest go [into it] to see the plague, that all that [is] in the house be not made unclean: and afterward the priest shall go in to see the house:

And he shall look on the plague, and, behold, [if] the plague [be] in the walls of the house with hollow strakes, greenish or reddish, which in sight [are] lower than the wall;

And the priest shall come again the seventh day, and shall look: and, behold, [if] the plague be spread in the walls of the house;

Then the priest shall command that they take away the stones in which the plague [is], and they shall cast them into an unclean place without the city: