Leviticus 13:47

"The garment also that the plague of leprosy is in, whether it be a woolen garment, or a linen garment; whether it be in warp, or woof; of linen, or of woolen; whether in a skin, or in any thing made of skin; if the plague be greenish or reddish in the garment, or in the skin, or in the warp, or in the woof, or any thing of skin; it is the plague of leprosy, and shall be showed unto the priest: and the priest shall look upon the plague, and shut up that which hath the plague seven days: 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 the skin, whatever service skin is used for; the plague is a fretting leprosy; it is unclean. And he shall burn the garment, whether the warp or the woof, in woolen, or in linen, or any thing of skin, wherein the plague is: for it is a fretting leprosy; it shall be burnt in the fire."

Various kinds of rot, canker, mildew, and insect infestation are known to attack woolen or linen garments; and these seem to be in view here. The ancient word "fretting" is of interest because it occurs in the British Book of Common Prayer and in Psalms 39:11, "like as it were a moth fretting a garment."

Once cloth is woven, there is no way to separate the warp and the woof, and the obvious separation of the two in this passage shows that not only woven and completed garments were in view, but also the yarn made ready for the weaving and found to be infected before the weaving took place. The danger of infection from the use of infected clothing was the basis for the prohibitions here. Careful watchfulness marked their efforts to refrain from destroying any garment. Garments, in those days, were precious property.