ויקרא, פרק י״ד, פסוק ל״ט

The inspection of a home afflicted with a severe plague requires a deliberate one-week waiting period, after which the priest returns to evaluate the situation. This phenomenon is not viewed simply as physical decay taking hold of a building. Rather, it serves as a direct punishment for the sin of malicious gossip. Because harmful speech sows hatred, drives people apart, and destroys peaceful coexistence, the resulting affliction strikes directly at the offender's personal sanctuary—their home [אדרת אליהו - ר' יוסף חיים].

The follow-up examination must be conducted specifically during the daytime hours of the seventh day, never at night [מלבי"ם, אדרת אליהו]. Upon his return, the priest carefully assesses whether the decay has expanded or migrated to other walls [ביאור שטיינזלץ], which would indicate that the rot is actively consuming the structure [רלב"ג]. In certain cases, the initial outbreak is so severe that its subsequent expansion is entirely expected and obvious from the start [העמק דבר].

When determining if the affliction has grown, the new signs of decay do not need to be physically connected to the original spot. However, the required size of the expansion depends on its location. If the new mark is directly adjacent to the original affliction, even the most microscopic growth is considered a spread. Conversely, if the new mark appears further away on the wall, it must meet a specific minimum size to be classified as an expansion [רלב"ג, אדרת אליהו, פירושי רד"צ הופמן]. Furthermore, these strict laws of impurity apply exclusively to the walls of the primary residence. Secondary structures or attached additions, such as balconies, feeding troughs, partitions, storehouses, or bathhouses, are entirely exempt from these rules [תורה תמימה, מלבי"ם, אדרת אליהו].

While the consequences of a spreading affliction are clear, a question arises regarding a plague that remains entirely unchanged after the first week. One perspective suggests that in such a scenario, the house is immediately declared pure, requiring no further intervention [בכור שור]. However, the primary approach among commentators asserts that the home is not cleared so quickly. Instead, the priest quarantines the house for a second week. At the conclusion of this additional waiting period, regardless of whether the affliction has finally spread or remained stagnant, the affected stones must be extracted, the old plaster scraped away, and the wall entirely replastered [ביאור יש"ר, פירושי רד"צ הופמן].