Leviticus 13:57 (KJV)

And the priest shall look on the plague, after that it is washed: and, behold, if the plague have not changed his colour, and the plague be not spread; it is unclean; thou shalt burn it in the fire; it is fret inward, whether it be bare within or without.

And if the priest look, and, behold, the plague be somewhat dark after the washing of it; then he shall rend it out of the garment, or out of the skin, or out of the warp, or out of the woof:

And if it appear still in the garment, either in the warp, or in the woof, or in any thing of skin; it is a spreading plague: thou shalt burn that wherein the plague is with fire.

And the garment, either warp, or woof, or whatsoever thing of skin it be, which thou shalt wash, if the plague be departed from them, then it shall be washed the second time, and shall be clean.

This is the law of the plague of leprosy in a garment of woollen or linen, either in the warp, or woof, or any thing of skins, to pronounce it clean, or to pronounce it unclean.