Commentaire sur Nega'im 13:5

הבונה מן המוסגר בטהור – after he had torn out and scraped and [re-] plastered and gave it a week, within the days of [the house] being shut up he took from that same house stones and built them in another house.

If one who builds in cleanliness with stones from a house that was isolated and the nega returned to the [former] house, the stones must be taken out. The stones were taken out of a house that was isolated and then used to build a clean house elsewhere. If the nega returns to the former house, the stones in the new house are still considered part of the afflicted house and therefore they must be removed from the new house and discarded.

וחזר נגע לבית – that was shut up/quarantined.

If it returned to the stones, the first house must be torn down, and the stones serve the second house while the signs are under observation. If the nega reappears in the stones themselves, then the first house must still be torn down, as if the nega returned to the house itself. The second house now begins the process of a house afflicted by a nega. The stones remain in the house and they serve as the basis to see if the nega spreads at the end of the second week.

חולץ את האבנים – that he took from it, and removes them from the pure [house], and they are impure like the uncleanness of the house that he took them from.

חזר הנגע לאבנים – that he built in the pure [new] house.

הבית – that is shut up, should be torn down/chipped off, as if they were fixed in it. And they stones also require tearing out, but that we wait for them until they will serve in the second house [for the purpose of inspecting whether] tokens [of uncleanness recur in the second house] , that require shutting up/quarantining , and its law for every manner like every house in which a plague appears at the outset.