Extra Credit · Parallel Chazal
English: The priest shall examine the lesion and isolate the affected article for seven days.
Chabad.org — Rashi for Vayikra 13:50
Sifra (Toras Kohanim), Tazria, Parashat Nega'im 14:7–8 (Vayikra 13:50)
English: “The priest shall examine the lesion and quarantine the lesion for seven days”—initially. “On the seventh day”—one might think the seven days include both day and night; Scripture says “on the day,” not at night.
The Sifra identifies the first seven-day quarantine as the initial stage and requires the seventh-day examination to take place in daylight, not at night.