Daylight Purification

This shall be the law of the metzora in the day of his purification: he shall be brought to the Kohen.                                                                  Leviticus 14:2

The verse’s wording “in the day of his purification” teaches that a metzora may not be declared pure at night.     Rashi

Just as the halacha established that the “plagues” discussed in our parasha cannot be examined by a Kohen at night, and therefore, impurity cannot be declared at night, so too the Kohen may not declare purity at night.

The symbolism of the halachic approach is that we must not use candles to look for faults in our fellow man (as noted, our Sages teach that tzara’at is punishment for speaking evil of others [lashon hara] and other shortcomings).

Equally, one can be cured only in the light of day, that is, when the metzora becomes aware of his faults and repents.