Leviticus 13:51

And he shall look on the plague on the seventh day: if the plague be spread in the garment, either in the warp, or in the woof, or in a skin, or in any work that is made of skin; the plague is a fretting leprosy; it is unclean.

Cross-reference

Leviticus 13:48 defines which fabrics (warp, woof, leather) are affected — this verse builds on that list.

Leviticus 14:44 applies the same rule: if the plague spreads after containment, the house is declared unclean.

Leviticus 14:39 describes the priest's return after seven days to re-inspect a house — parallel to this garment inspection.