Positive commandment · Mitzvat Aseh #103 of 613
For a house afflicted with tzara’at to impart impurity
להיות בית מנוגע מטמא
The verse · Vayikra 14:34
כִּי תָבֹאוּ אֶל־אֶרֶץ כְּנַעַן אֲשֶׁר אֲנִי נֹתֵן לָכֶם לַאֲחֻזָּה וְנָתַתִּי נֶגַע צָרַעַת בְּבֵית אֶרֶץ אֲחֻזַּתְכֶם
“When you come into the land of Kena῾an, which I give to you for a possession, and I put the plague of żara῾at in a house of the land of your possession;”
The Rambam’s words
For a house afflicted with tzara’at to impart impurity.
להיות בית מנוגע מטמא.
Who & when
“And it is practiced in the house of a male or female in the Land [of Israel], at any time that there are priests fitting for the thing.”
Where in the Mishneh Torah
Hilchot Defilement by Leprosy הלכות טומאת צרעת