Leviticus 14:46

Moreover he that goeth into the house all the while that it is shut up shall be unclean until the even.

This instruction belongs to God's directions to Moses concerning houses and cleanliness. The house was shut up because it was unsafe. Anyone who went into the house during the whole time that it was shut up became unclean until the evening. Those who served God were to preserve order and cleanliness in everything.