הלכה אויף ויקרא 15:2

Zavim; zavot; menstruants; women who have just given birth; and all others who leave a state of ritual impurity for a state of ritual purity in the middle of the festival—these are surely permitted to launder their clothing. And one who only has one cloak—such a one can surely launder it on the festival. Hand towels; barbers’ towels; and body-drying towels—these may surely be laundered on the festival. And likewise may we launder linen garments on the festival—as they need constant laundering, even if they were laundered on the eve of the holiday.

The commandment of the matter of impurity of a zav (one with a discharge) to be impure and to render impure: That a zav be impure and render others impure, as it is stated (Leviticus 15:2-3), “when there be any man with a discharge from his flesh, etc.” And the explanation comes, “from his flesh,” is meaning a flow from the orifice of the member. And [it is] as they, may their memory be blessed, expounded, “‘When there be a discharge’ — it is possible, a discharge from any place would be impure. [Hence,] we learn to say, ‘from his flesh’ and not all of his flesh. Once Scripture has distinguished between flesh and flesh, I have merited to learn out the law of impurity with a zav and with a zavah. Just like a zavah is from the place that she becomes impure, etc.”